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>

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.

Effect of Particle Size on Oxidation Reaction Kinetics Parameter of Cu2O Powders

2011 ◽  
Vol 284-286 ◽  
pp. 726-729 ◽  
Author(s):  
Zai Yuan Li ◽  
Yu Chun Zhai ◽  
Myongil Pang
Keyword(s):  
Activation Energy ◽  
Particle Size ◽  
Apparent Activation Energy ◽  
Reaction Kinetics ◽  
Oxidation Reaction ◽  
Raw Materials ◽  
Particle Sizes ◽  
Oxide Powders ◽  
Effect Of Particle Size ◽  
Kinetics Parameter

The 0.4mol•L-1CuSO4liquor and 5mol•L-1NaOH liquor were prepared by CuSO4·5H2O and NaOH as raw materials. The Cu2O powders were prepared by dextrose reducer and PVP dispersant. The Cu2O oxidation reaction DTA-TG-DTG curves were obtained by SDT 2960 simultaneous DSC-TGA analysis apparatus. The mensuration condition were that rise temperature velocity 15°C·min-1and deoxidize gas air. The Cu2O oxidation reaction kinetics was calculated by DTA-TG-DTG curves data. The results indicate that the cuprous oxide powders shape were spherical, their particle’ sizes were 100,200,1000nm. Their apparent activation energy were 164.38, 175.54, 282.65 KJ·mol-1, the apparent activation energy increase with Cu2O particle’ size. Their frequency factors were 1.22×1013, 1.40×1013, 2.88×1020, the frequency factors increase with particle’ size Cu2O. Their reaction progressions were 1.02, 1.00, 0.96, the reaction progression increase with Cu2O particle’ size decreased.

scholarly journals Effect of the Particle Size of Iron Ore on the Pyrolysis Kinetic Behaviour of Coal-Iron Ore Briquettes

Energies ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 2595 ◽  
Author(s):  
Heng Zheng ◽  
Wei Wang ◽  
Runsheng Xu ◽  
Rian Zan ◽  
Johannes Schenk ◽  
...  
Keyword(s):  
Activation Energy ◽  
Particle Size ◽  
Synergistic Effect ◽  
Apparent Activation Energy ◽  
Conversion Rate ◽  
Iron Ore ◽  
High Reactivity ◽  
Particle Sizes ◽  
Low Carbon ◽  
Pyrolysis Behaviour

High reactivity coke is beneficial for achieving low carbon emission blast furnace ironmaking. Therefore, the preparation of highly reactive ferro-coke has aroused widespread attention. However, the effects of the particle size of iron ore on the pyrolysis behaviour of a coal-iron ore briquette are still unclear. In this study, the effect of three particle sizes (0.50–1.00 mm, 0.25–0.50 mm and <0.74 mm) of iron ore on the thermal and kinetic behaviours of coal-iron ore briquettes were investigated by non-isothermal kinetic analysis. The results showed that the synergistic effect of iron ore and coal during coking mainly occurred during the later reaction stage (850–1100 °C) and smaller particle sizes of iron ore have a stronger synergistic effect. The addition of iron ore had little effect on T0 (the initial temperature) and Tp (the temperature at the maximum conversion rate) of briquette pyrolysis, however itgreatly affected the conversion rate and Tf (the final temperature) of the briquettes. T0 decreased with the decrease of iron ore particle sizes, while Tp and Tf showed opposite trends. After adding iron ore into the coal briquette, the reaction kinetics at all stages of the coal-iron ore briquettes changed. The weighted apparent activation energy of the caking coal (JM) briquette was 35.532 kJ/mol, which is lower than that of the coal-iron ore briquettes (38.703–55.627 kJ/mol). In addition, the weighted apparent activation energy gradually increased with decreasing iron ore particle sizes.

The decomposition of nitrous oxide catalysed by palladium-gold alloy wires

1966 ◽  
Vol 294 (1436) ◽  
pp. 1-19 ◽  
Keyword(s):  
Activation Energy ◽  
Nitrous Oxide ◽  
Fermi Level ◽  
Apparent Activation Energy ◽  
Frequency Factor ◽  
Kcal Mole ◽  
Dissociative Chemisorption ◽  
Retarding Effect ◽  
Effect Of Oxygen ◽  
Decomposition Of Nitrous Oxide

The rate of decomposition of nitrous oxide has been examined by pressure measurements, at temperatures between 500 and 900 °C and pressures between 10 -2 and 1 torr. The reaction is first order, but shows retardation by oxygen, but not nitrogen. Over the range of alloys, from Pd to nearly 40 at. % Pd, the velocity at 650 °C falls by a factor of 104, the apparent activation energy falls from 30 to 13 kcal/mole, and the retarding effect of oxygen falls to zero. Over this range of alloys the Fermi level which lies in the d band hardly changes but the concentration of the d band vacancies falls to zero. Over the range of alloys from 40 at. % Pd to Au the velocity at 650 °C remains constant but the apparent activation energy and frequency factor, which show an abrupt increase at 40 at. % Pd, show a continuous fall. The retarding effect of oxygen remains zero. In this range the Fermi level has entered the s band and increases to Au. A steady state treatment of an irreversible dissociative chemisorption of nitrous oxide, together with an oxygen chemisorption equilibrium, yields an equation for the velocity in quantitative agreement with the results found. It is also possible to account for the increase in apparent activation energy with oxygen coverage of the surface. The heat of adsorption of oxygen is derived as 32-2±2 kcal/mole, and the activation energy for chemisorption of nitrous oxide as 12-7 ±0-5 kcal/mole.

Calculations of activation energy and frequency factors for corn leafs pyrolysis using excel solver: new concept

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Omar Salim Al-Ayed ◽  
Mohammad Waleed Amer ◽  
Sura Al-Harahshah ◽  
Birgit Maaten ◽  
Muhammad Sajjad Ahmed
Keyword(s):  
Activation Energy ◽  
Apparent Activation Energy ◽  
Frequency Factor ◽  
Heating Rates ◽  
First Order ◽  
First Order Kinetics ◽  
Calculated Activation Energy ◽  
Apparent Activation Energies ◽  
Excel Solver ◽  
Calculated Activation

Abstract Thermal degradations of biomass corn leaves were studied for kinetic modeling. Thermogravimetric-differential analyzer runs at 5, 10, 20, and 30 °C min−1 heating rates were employed. Apparent activation energy and frequency factor values were calculated for first-order kinetics using several procedures. The procedure of Coats and Redfern showed 28.89 to 31.78 kJ mol−1 apparent activation energy and 15.5 to 157.12 min−1 frequency factor, respectively. Calculation of the apparent activation energy and frequency factor using Kissinger–Akahira–Sunose procedure gave 229.9–364.2 kJ/mol and 8.567 × 1023 and 1.13 × 1031 (min−1), respectively as the conversion increased from 0.1 to 0.9. The newly introduced excel solver procedure indicates a distribution activation energy over the entire range of conversion. For first-order reaction kinetics, the calculated apparent activation energy magnitudes ranged between 5.0 kJ mol−1 with frequency factor equals to 0.239 and 196.2 kJ mol−1 with frequency factor 2.89 × 1012 in the studied range. The low or high magnitudes of the calculated activation energy are not associated with a particular value of the conversion. The calculated apparent activation energies are related to the direct solution of the simultaneous equations that constitute the basis of the excel solver.

scholarly journals Study on the Size-Dependent Oxidation Reaction Kinetics of Nanosized Zinc Sulfide

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Qing-Shan Fu ◽  
Yong-Qiang Xue ◽  
Zi-Xiang Cui ◽  
Ming-Fang Wang
Keyword(s):  
Activation Energy ◽  
Particle Size ◽  
Surface Energy ◽  
Apparent Activation Energy ◽  
Zinc Sulfide ◽  
Rate Constant ◽  
Oxidation Reaction ◽  
Reaction Order ◽  
Preexponential Factor ◽  
Surface Entropy

Numerous oxidation problems of nanoparticles are often involved during the preparation and application of nanomaterials. The oxidation rate of nanomaterials is much faster than bulk materials due to nanoeffect. Nanosized zinc sulfide (nano-ZnS) and oxygen were chosen as a reaction system. The influence regularities were discussed and the influence essence was elucidated theoretically. The results indicate that the particle size can remarkably influence the oxidation reaction kinetics. The rate constant and the reaction order increase, while the apparent activation energy and the preexponential factor decrease with the decreasing particle size. Furthermore, the logarithm of rate constant, the apparent activation energy and the logarithm of preexponential factor are linearly related to the reciprocal of particle diameter, respectively. The essence is that the rate constant is influenced by the combined effect of molar surface energy and molar surface entropy, the reaction order by the molar surface area, the apparent activation energy, by the molar surface energy, and the preexponential factor by the molar surface entropy. The influence regularities and essence can provide theoretical guidance to solve the oxidation problems involved in the process of preparation and application of nanomaterials.

scholarly journals The Kinetic Parameters of Carbonaceous Materials Activated with Potassium Hydroxide

2000 ◽  
Vol 18 (6) ◽  
pp. 573-580 ◽  
Author(s):  
Zou Yong ◽  
Han Bu-Xing
Keyword(s):  
Activation Energy ◽  
Apparent Activation Energy ◽  
Kinetic Parameters ◽  
Petroleum Coke ◽  
Potassium Hydroxide ◽  
Formation Energy ◽  
Frequency Factor ◽  
Carbonaceous Materials ◽  
Activation Temperature

On the basis of micropore formation in carbonaceous materials, the activation energy for the potassium hydroxide activation of Chinese petroleum coke and coal has been deduced theoretically as dB0/dt = A exp(–Ea∈/RT), where ∈ is the formation energy for the metastable solid formed at the activation temperature. The kinetic parameters (frequency factor, A, and apparent activation energy, Ea) were calculated from this equation as being 5.319 mg/(g min), 36.51 kJ/mol and 6.64 mg/(g min), 49.46 kJ/mol, respectively, for the two carbonaceous materials studied.

scholarly journals Effect of Nano-Magnesium Hydride on the Thermal Decomposition Behaviors of RDX

2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Miao Yao ◽  
Liping Chen ◽  
Guoning Rao ◽  
Jianxin Zou ◽  
Xiaoqin Zeng ◽  
...  
Keyword(s):  
Activation Energy ◽  
Thermal Stability ◽  
Thermal Decomposition ◽  
Apparent Activation Energy ◽  
Frequency Factor ◽  
High Heat ◽  
Magnesium Hydride ◽  
Probable Mechanism ◽  
Kinetic Properties ◽  
Calculation Results

In order to improve the detonation performance of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) explosive, addictives with high heat values were used, and magnesium hydride (MgH2) is one of the candidates. However, it is important to see whether MgH2is a safe addictive. In this paper, the thermal and kinetic properties of RDX and mixture of RDX/MgH2were investigated by differential scanning calorimeter (DSC) and accelerating rate calorimeter (ARC), respectively. The apparent activation energy (E) and frequency factor (A) of thermal explosion were calculated based on the data of DSC experiments using the Kissinger and Ozawa approaches. The results show that the addition of MgH2decreases bothEandAof RDX, which means that the mixture of RDX/MgH2has a lower thermal stability than RDX, and the calculation results obtained from the ARC experiments data support this too. Besides, the most probable mechanism functions about the decomposition of RDX and RDX/MgH2were given in this paper which confirmed the change of the decomposition mechanism.

The Effects of Particle Size on the Kinetic Parameters in the Reaction of Nano-Nio with Sodium Bisulfate Solution

2011 ◽  
Vol 36 (4) ◽  
pp. 329-341 ◽  
Author(s):  
Yongqiang Xue ◽  
Xiaopeng Wang ◽  
Zixiang Cui
Keyword(s):  
Activation Energy ◽  
Particle Size ◽  
Apparent Activation Energy ◽  
Kinetic Parameters ◽  
Rate Constant ◽  
Reaction Order ◽  
Particle Diameter ◽  
Preexponential Factor ◽  
Exponential Factor ◽  
Sodium Bisulfate

The kinetic parameters for the chemical reaction of nano-NiO of different particle sizes with aqueous sodium bisulfate solution were determined; additionally, the influence of particle size on the kinetic parameters were studied and were discussed. The results show that: there are clear effects of the particle size of nano-NiO on the rate constant, the reaction order, the apparent activation energy and the pre-exponential factor; thus the rate constant and the reaction order increase, and the apparent activation energy and the pre-exponential factor decrease, with decrease of the particle diameter; the logarithm of the preexponential factor, and the apparent activation energy, exhibit a linear relationship with the reciprocal of the particle diameter respectively. The bases of the role of the particle size are that the reaction order is influenced by the molar surface area of nano-NiO, the apparent activation energy by the molar surface energy, the preexponential factor by the molar surface entropy, and the rate constant by both the molar surface energy and the molar surface entropy.

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