Kinetic Analysis of Co-Firing of Corn Stalk and Paper Sludge Using Model-Fitting and Model-Free Methods

2019 ◽  
Vol 142 (4) ◽  
Author(s):  
Yanshan Yin ◽  
Boming Yang ◽  
Jie Yin ◽  
Hong Tian ◽  
Wei Zhang ◽  
...  
Keyword(s):  
Activation Energy ◽  
High Reliability ◽  
Model Fitting ◽  
Combustion Characteristic ◽  
Paper Sludge ◽  
Corn Stalk ◽  
Characteristic Index ◽  
Average Activation Energy ◽  
Model Free ◽  
Fitting Method

Abstract The combustion kinetics of corn stalk (CS), paper sludge (PS), and their mixture were studied by thermogravimetric analysis (TGA) using one model-fitting method (Coats–Redfern (CR)) and four model-free methods, namely, Flynn–Wall–Ozawa (FWO), Kissinger–Akahira–Sunose (KAS), Starink, and Friedman methods. TGA experiments were carried out at three different heating rates (10, 20, and 30 °C min−1) and with different weight percentages of PS in the mixture (0%, 20%, 50%, 80%, and 100%). The comprehensive combustion characteristic index decreases with an increase in the weight percentage of PS in the blends and increases with the increasing heating rate. Significant interactions occur in the co-firing of the blends containing 20% and 50% of PS. The co-firing kinetic parameters determined by the CR method show relatively high reliability due to the high correlation coefficient obtained from the linear fitting. The values of average activation energy determined by the model-fitting method are generally lower than those calculated from model-free methods. The co-firing of the blends containing 20% of PS shows the highest comprehensive combustion characteristic index and the lowest average activation energy based on the model-free methods.

scholarly journals Thermal Decomposition Mechanism and Kinetics Study of Plastic Waste Chlorinated Polyvinyl Chloride

Polymers ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 2080 ◽  
Author(s):  
Ru Zhou ◽  
Biqing Huang ◽  
Yanming Ding ◽  
Wenjuan Li ◽  
Jingjing Mu
Keyword(s):  
Activation Energy ◽  
Polyvinyl Chloride ◽  
Reaction Order ◽  
Model Fitting ◽  
Reaction Model ◽  
Order Reaction ◽  
Order Model ◽  
Model Free ◽  
Fitting Method ◽  
Two Stages

Chlorinated polyvinyl chloride (CPVC), as a new type of engineering plastic waste, has been used widely due to its good heat resistance, mechanical properties and corrosion resistance, while it has become an important part of solid waste. The pyrolysis behaviors of CPVC waste were analyzed based on thermogravimetric experiments to explore its reaction mechanism. Compared with polyvinyl chloride (PVC) pyrolysis, CPVC pyrolysis mechanism was divided into two stages and speculated to be dominated by the dehydrochlorination and cyclization/aromatization processes. A common model-free method, Flynn-Wall-Ozawa method, was applied to estimate the activation energy values at different conversion rates. Meanwhile, a typical model-fitting method, Coats-Redfern method, was used to predict the possible reaction model by the comparison of activation energy obtained from model-free method, thereby the first order reaction-order model and fourth order reaction-order model were established corresponding to these two stages. Eventually, based on the initial kinetic parameter values computed by model-free method and reaction model established by model-fitting method, kinetic parameters were optimized by Shuffled Complex Evolution algorithm and further applied to predict the CPVC pyrolysis behaviors during the whole temperature range.

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.

scholarly journals Dynamic Model-Free and Model-Fitting Kinetic Analysis during Torrefaction of Oil Palm Frond Pellets

2020 ◽  
Vol 15 (1) ◽  
pp. 253-263
Author(s):  
Sharmeela Matali ◽  
Norazah Abd Rahman ◽  
Siti Shawalliah Idris ◽  
Nurhafizah Yaacob
Keyword(s):  
Activation Energy ◽  
Thermal Degradation ◽  
Oil Palm ◽  
Model Fitting ◽  
Integral Model ◽  
Model Free ◽  
Solid Biofuel ◽  
Oil Palm Frond ◽  
Kinetics Of ◽  
Palm Frond

Torrefaction is a thermal conversion method extensively used for improving the properties of biomass. Usually this process is conducted within a temperature range of 200-300 °C under an inert atmosphere with residence time up to 60 minutes. This work aimed to study the kinetic of thermal degradation of oil palm frond pellet (OPFP) as solid biofuel for bioenergy production. The kinetics of OPFP during torrefaction was studied using frequently used iso-conversional model fitting (Coats-Redfern (CR)) and integral model-free (Kissinger-Akahira-Sunose (KAS)) methods in order to provide effective apparent activation energy as a function of conversion. The thermal degradation experiments were conducted at four heating rates of 5, 10, 15, and 20 °C/min in a thermogravimetric analyzer (TGA) under non-oxidative atmosphere. The results revealed that thermal decomposition kinetics of OPFP during torrefaction is significantly influenced by the severity of torrefaction temperature. Via Coats-Redfern method, torrefaction degradation reaction mechanism follows that of reaction order with n = 1. The activation energy values were 239.03 kJ/mol and 109.28 kJ/mol based on KAS and CR models, respectively. Copyright © 2020 BCREC Group. All rights reserved 

Thermogravimetric Experimental Study on Combustion Performance of Co-Firing of Sludge, Coal and Biomass in Micro-Oxygen-Rich Environment

2015 ◽  
Vol 768 ◽  
pp. 96-107 ◽  
Author(s):  
Li Jun Fang ◽  
Tong Cao ◽  
Hong Kun Liu ◽  
Chang Li
Keyword(s):  
Activation Energy ◽  
Combustion Characteristic ◽  
Biomass Combustion ◽  
Mixing Ratio ◽  
Analysis Method ◽  
Characteristic Index ◽  
Mixed Sample ◽  
Combustion Performance ◽  
Mixing Proportion ◽  
Burnout Rate

In order to study the combustion characteristics of sludge, coal, biomass and the mixed sample in micro-oxygen-rich environment (simulating micro-oxygen-rich environment with 30%O2/70%CO2), thermogravimetric analysis method is used in the paper. The experimental results show that under the micro-oxygen-rich environment, sludge has low ignition temperature, the average burning rate, burnout rate and flammability index, so combustion performance of sludge alone is poor and the weightlessness is more obvious in 200~600°C. But after mixing coal or biomass, combustion performance of sludge is improved. We use comprehensive application of flammability index and burnout characteristics index to determine the best mixing ratio is about 65% of sludge and coal, about 45% of sludge and biomass. Comprehensive combustion characteristic index may not be suitable for determining combustion performance of the sludge and its samples by comparison to S under the optimum mixing ratio of the sample and there are some errors. Biomass activation energy is the largest, the activation energy of sludge minimal. But the activation energy of the mixed sample doesn’t change regularly with the increase of sludge mixing proportion. So there is a deviation that we determine the mixing characteristics by a simple comparison of the activation energy of the samples. This paper provides a theoretical and data support for the selection and calculation of combustion parameters of mixed sludge and resource utilization of sludge.

Kinetic Studies on the Thermal Synthesis of Fluorapatite: Model Free and Model-Fitting Methods

2018 ◽  
Vol 28 ◽  
pp. 75-89
Author(s):  
Hamid Reza Javadinejad ◽  
Sayed Ahmad Hosseini ◽  
Mohsen Saboktakin Rizi ◽  
Eiman Aghababaei ◽  
Hossein Naseri
Keyword(s):  
Activation Energy ◽  
Model Fitting ◽  
Kinetic Studies ◽  
Isoconversional Methods ◽  
Reaction Model ◽  
Heating Rates ◽  
Thermal Synthesis ◽  
Exponential Factor ◽  
Model Free ◽  
Master Plots

The kinetic study for the synthesis of Fluorapatite has been done using the thermogravimetric technique under non-isothermal conditions and at four heating rates of 5, 10, 15 and 20 °C. Both model free and model-fitting methods were used to investigate kinetic parameters. Calcium oxide, phosphorus pentoxide and calcium fluoride were used as the precursor materials. The activation energy values were calculated through model-fitting and isoconversional methods and were used to predict the reaction model and pre-exponential factor. In this case several techniques were considered such as master plots and compensation effects. The results indicated that the reaction mechanism was chemically controlled with second and third order reaction models in the whole range of conversion which the activation energy varied from 25 to 43 kJ/mol.

scholarly journals Influence of coal properties on the co-combustion characteristics of low-grade coal and city mud

2014 ◽  
Vol 16 (2) ◽  
pp. 329-338 ◽  
Keyword(s):  
Activation Energy ◽  
Particle Size ◽  
Apparent Activation Energy ◽  
Frequency Factor ◽  
Combustion Characteristic ◽  
Low Grade ◽  
Mixing Ratio ◽  
Mixture Ratio ◽  
Characteristic Index ◽  
Carbon Burning

<div> <p>In this paper, the effects of the mixing ratio and particle size of coal were investigated using a thermogravimetric analysis (TGA). A method of Achar-Brindley-Sharp-Wendworth (ABSW) was applied to a simultaneous calculation of the kinetic parameters (including the apparent activation energy, the reaction order and the frequency factor). Meanwhile, this study also revealed that both the burning performance and the characteristic parameters improved when sludge mixing ratio was smaller (10 wt.%). The ignition temperature advanced with an increase of the sludge proportion, while the combustion characteristic index dropped. As the sludge mixture ratio rose to 70 wt.%, the DTG curve reached three peaks at 293 &deg;C, 580 &deg;C and 748 &deg;C Decreasing the coal particle size led to the advancement of the devolatilization, fixed carbon burning stage and maximum weight loss rate, and the reduction of the corresponding temperature. Additionally, the apparent activation energy and frequency factor of the mixture reduced when the proportion of the sludge mixing ratio went up. Also, the experiment results indicated that with the decline of the particle size distribution of coal, the apparent activation energy followed a downward trend, while the frequency factor increased.</p> </div> <p>&nbsp;</p>

Isothermal oxidation kinetics and oxidation behavior of nickel slag

2020 ◽  
Vol 117 (6) ◽  
pp. 603
Author(s):  
Xiaoming Li ◽  
Xinyi Zhang ◽  
Yi Li ◽  
Xiangdong Xing
Keyword(s):  
Activation Energy ◽  
Oxidation Behavior ◽  
Model Fitting ◽  
Three Dimensional ◽  
Oxidation Kinetic ◽  
Isothermal Oxidation ◽  
Model Free ◽  
Random Nucleation ◽  
Higher Temperature ◽  
Lower Temperature

To improve the reduction effect of nickel slag in preparing Fe–Co–Ni–Cu alloy, an oxidization pretreatment was carried out to changing the structure and phase of silicate and sulfide for the nickel slag before the reducing process. The oxidation behavior and kinetics of nickel slag under different temperature and time conditions were discussed. The results shown that in the oxidation process of nickel slag, the part of Fe2SiO4 was oxidized to Fe3O4 and further to Fe2O3, and the other part of Fe2SiO4 directly oxidized to Fe2O3. Meanwhile, the nickel, cobalt and copper in the form of silicate and sulfide were changed into oxides. The changes of the phases are beneficial to the subsequent reduction of nickel slag. The oxidation degree of nickel slag reached 98% under suitable oxidation conditions (900 °C, 15 min). The oxidation kinetic model of nickel slag obtained by Ln–Ln analysis and Model-fitting method was three-dimensional diffusion at lower temperature (300 °C, 400 °C and 500 °C) and random nucleation at higher temperature (700 °C, 900 °C and 1000 °C) respectively. The activation energies obtained by the model method and the model-free method were 28.58 kJ.mol−1 and 26.28 kJ.mol−1 at lower temperature (300 °C, 400 °C and 500 °C) respectively, and the corresponding value were 81.98 kJ.mol−1 and 78.36 kJ.mol−1 at higher temperature (700 °C, 900 °C and 1000 °C) respectively. The activation energy calculated by the two methods was relatively close, and both can be used to calculate the activation energy.

Thermal degradation kinetics and lifetime of HDPE/PLLA/pro-oxidant blends

2016 ◽  
Vol 36 (9) ◽  
pp. 917-931 ◽  
Author(s):  
Gaurav Madhu ◽  
Dev K. Mandal ◽  
Haripada Bhunia ◽  
Pramod K. Bajpai
Keyword(s):  
Activation Energy ◽  
Thermal Degradation ◽  
Degradation Kinetics ◽  
Model Fitting ◽  
Frequency Factor ◽  
Thermal Degradation Kinetics ◽  
Heating Rates ◽  
Model Free ◽  
Calculation Technique ◽  
Thermal Degradation Behavior

Abstract The effect of adding poly(L-lactic acid) (PLLA) with and without a pro-oxidant additive cobalt stearate (CoSt) and compatibilizer maleic anhydride grafted polyethylene (MA-g-PE) on the thermal degradation and stability of high-density polyethylene (HDPE) films was analyzed using thermogravimetric analysis (TGA). The kinetic parameters [i.e. activation energy (Ea), order of reaction (n), and frequency factor ln(A)] of the samples were studied over a temperature range of 25°C–600°C at four heating rates (i.e. 5, 10, 15, and 20°C/min) through model-free techniques (e.g. Friedman, second Kissinger, and Flynn-Wall-Ozawa) and model-fitting techniques (e.g. Freeman-Carroll and Kim-Park). The value of Ea for neat HDPE was found to be much higher than PLLA; for the HDPE/PLLA blend, it was nearer to that of HDPE. An increase in the activation energy of 80/20 (HDPE/PLLA) blend was noticed by the addition of MA-g-PE. The TGA data and degradation kinetics were also used to predict the lifetime of the film samples. The lifetime of HDPE was found to decrease with the increase in the concentration of CoSt, thereby revealing its pro-oxidative ability. Minimum lifetime was noted for the HDPE/PLLA (80/20) sample blended with CoSt, which increased slightly in the presence of MA-g-PE. Studies indicated that the thermal degradation behavior and lifetime of the investigated film samples depends not only on the fractions of their constituents but also on the heating rates and calculation technique.

scholarly journals Kinetic analysis of CO2 gasification of biochar and anthracite based on integral isoconversional nonlinear method

2020 ◽  
Vol 39 (1) ◽  
pp. 527-538
Author(s):  
Bing Dai ◽  
Jia-Yong Qiu ◽  
Shan Ren ◽  
Bu-Xin Su ◽  
Xiang Ding ◽  
...  
Keyword(s):  
Activation Energy ◽  
Early Stage ◽  
Model Fitting ◽  
Preexponential Factor ◽  
Single Step ◽  
Conversion Degree ◽  
Nonlinear Method ◽  
Gasification Reactivity ◽  
Model Free ◽  
Gasification Process

AbstractThe nonisothermal thermogravimetric analysis was implemented for gasification of sawdust char (SD-char), wheat straw char (WS-char), rice husk char (RH-char), bamboo char (BB-char) and anthracite coal (AC) in the presence of CO2. The dependence of activation energy upon conversion for different biochars and AC was obtained by the integral isoconversional nonlinear (NL-INT) method which is a model-free method. Based on the activation energy values from the NL-INT method, a model-fitting method called random pore model (RPM) was used to estimate the kinetic parameters including the preexponential factor and pore structure parameter from the experimental data. The results are shown that the gasification reactivity of different samples from high to low can be sorted as that of WS-char, SD-char, BB-char, RH-char and AC. In the early stage of gasification, the activation energy values of biochars increase generally with an increase in the conversion degree, whereas the value of AC decreases. Thereafter, the activation energy values remain almost unchanged when the conversion is up to some extent. When the conversion degree varies between about 0.3 and 0.9, these carbon materials can be sorted in the order of average activation energy from low to high as WS-char, SD-char, AC, RH-char and BB-char, respectively, 134.3, 143.8, 168.5, 184.8 and 193.0 kJ/mol. It is shown that a complex multistep mechanism occurs in the initial stage of gasification, while a single-step gasification mechanism exists in the rest of the gasification process. The RPM is suitable for describing the gasification of biomass chars and AC except the initial gasification. Additionally, it is found that the kinetic compensation effect (KCE) still exists in the gasification reactions of biochars and AC. However, the AC deviates markedly from the KCE curve. This may be caused by the similarity of carbonaceous structure of biochars and the difference in reactivity between biochars and AC.

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