Non-isothermal thermogravimetric analysis of heavy oil in an O2/CO2 atmosphere

2018 ◽  
Vol 16 (6) ◽  
Author(s):  
Zhiqiang Wang ◽  
Ming Liu ◽  
Xingxing Cheng ◽  
Yusheng He ◽  
Yingjie Hu ◽  
...  
Keyword(s):  
Activation Energy ◽  
High Temperature ◽  
Thermogravimetric Analysis ◽  
Low Temperature ◽  
Oxygen Concentration ◽  
Heavy Oil ◽  
Combustion Process ◽  
Molecular Weights ◽  
Diffusion Controlled ◽  
Temperature Activation

Abstract Although heavy oil is an abundant and promising energy source, its processing and utilization are complicated due to its high density, low hydrogen/carbon ratio, and high asphaltene content. Fortunately, these problems can be mitigated by the application of oxy-fuel combustion. To gain deeper insights into the above technology, the characteristics of heavy oil combustion in an O2/CO2 atmosphere was investigated using non-isothermal thermogravimetric analysis. We demonstrate that the combustion process consisted of four stages. Low-molecular-weight hydrocarbons reacted at low temperature, whereas heavy ones required a higher temperature. Increasing the concentration of oxygen resulted in increased TGA and DSC peak intensities and decreased peak widths, and these peaks were shifted to lower temperatures. Coat-Redfern and Flynn-Wall-Ozzawa methods were used to evaluate the kinetic parameters (E, A) of the oxidation process, showing that the high-temperature activation energy was much higher than the low-temperature one due to the different molecular weights of the oxidized substrates in each region. The reaction was demonstrated to be diffusion-controlled, as reflected by the lower activation energy at high oxygen concentration and high temperature, with the influence of oxygen concentration on QO processes being much more obvious than that on SO ones.

Study on Co-Combustion of Oil Shale Semi-Coke and Corn Stalk

2012 ◽  
Vol 614-615 ◽  
pp. 103-106
Author(s):  
Hong Peng Liu ◽  
Wei Yi Li ◽  
Xu Dong Wang ◽  
Hao Xu ◽  
Guan Yi Chen ◽  
...  
Keyword(s):  
Activation Energy ◽  
High Temperature ◽  
Low Temperature ◽  
Oil Shale ◽  
Combustion Process ◽  
Combustion Characteristics ◽  
Corn Stalk ◽  
Kinetics Parameters ◽  
High Temperature Stage ◽  
Blend Ratios

Co-combustion experiment of oil shale semi-coke and corn stalk at different blend ratios was performed using thermogravimetric analyzer. The influence of different blend ratios has been studied. The combustion characteristics are obtained under the heating rates of 20oC/min and the experimental temperature range of 40-850oC. The combustion process of the blends is divided into three stages: low-temperature stage, transition stage and high-temperature stage. With the increasing of corn stalk in the blends, the reaction of combustion mainly shifts from high-temperature stage to low-temperature stage, and there is no obvious change for the ignition temperature, but the burn out temperature comes down. The combustion kinetics parameters of the blends were analyzed using Flynn-Wall-Ozawa model. The result shows that the activation energy of the volatile matter stage increases and the activation energy of semi-coke combustion stage decreases. The combustion characteristics of the oil shale semi-coke get improved significantly with the mixture of corn stalk.

Study of high-pressure air jet controlled compression ignition with compound thermodynamic cycle for combustion and emission formation process

2020 ◽  
pp. 146808742096933
Author(s):  
Xiangyu Meng ◽  
Sicheng Liu ◽  
Jingchen Cui ◽  
Jiangping Tian ◽  
Wuqiang Long ◽  
...  
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
Low Temperature ◽  
Formation Process ◽  
Combustion Process ◽  
Thermodynamic Cycle ◽  
Compression Ignition ◽  
Temperature Reaction ◽  
Air Jet ◽  
High Temperature Reaction

A novel method called high-pressure air (HPA) jet controlled compression ignition (JCCI) based on the compound thermodynamic cycle was investigated in this work. The combustion process of premixed mixture can be controlled flexibly by the high-pressure air jet compression, and it characterizes the intensified low-temperature reaction and two-stage high-temperature reaction. The three-dimensional (3D) computational fluid dynamics (CFD) numerical simulation was employed to study the emission formation process and mechanism, and the effects of high-pressure air jet temperature and duration on emissions were also investigated. The simulation results showed that the NOx formation is mainly affected by the first-stage high-temperature reaction due to the higher reaction temperature. Overall, this combustion mode can obtain ultra-low NOx emission. The second-stage high-temperature reaction plays an important role in the CO and THC formation caused by the mixing effect of the high-pressure air and original in-cylinder mixture. The increasing air jet temperature leads to a larger high-temperature in-cylinder region and more fuel in the first-stage reaction, and therefore resulting in higher NOx emission. However, the increasing air jet temperature can significantly reduce the CO and THC emissions. For the air jet duration comparisons, both too short and too long air jet durations could induce higher NOx emission. A higher air jet duration would result in higher CO emission due to the more high-pressure air jet with relatively low temperature.

INFLUENCE OF THE CROSSLINK STRUCTURE ON THE ACTIVATION ENERGY CALCULATED UNDER THERMO-OXIDATIVE CONDITIONS

2018 ◽  
Vol 91 (1) ◽  
pp. 205-224 ◽  
Author(s):  
Richard J. Pazur ◽  
T. Mengistu
Keyword(s):  
Activation Energy ◽  
Zinc Oxide ◽  
High Temperature ◽  
Oxidation Process ◽  
Activation Energies ◽  
Structure Stability ◽  
Temperature Oxidation ◽  
Network Chain ◽  
Temperature Activation ◽  
Sulfur Donor

ABSTRACT A series of six carbon black reinforced brominated poly(isobutylene-co-isoprene) (BIIR) compounds has been developed varying only in cure system type: sulfur, sulfur donor, zinc oxide, peroxide, phenolic resin, and ionic. Compounds were aged from room temperature up to 115 °C, and hardness, mechanical properties, and network chain density were measured. Non-Arrhenius behavior was observed due to data curvature from 70 to 85 °C. The oxidation process was adequately described by assigning low (23–85 °C) and high (85–115 °C) temperature regimes. Heterogeneous aging due to diffusion limited oxygen (DLO) occurred for heat aging above 85 °C, and all measured responses except tensile strength were strongly affected, causing lower activation energies. The activation energy for the high temperature oxidation process is in the range of 107 to 133 kJ/mol in the following ascending order: zinc oxide, ionic, sulfur donor, sulfur, peroxide, and resin. The midpoint of the high temperature activation energies is of the same order as the BIIR and poly(isobutylene) elastomers. The low temperature activation energy is in the range of 55–60 kJ/mol and is likely due to a combination of oxidative chain scission (crosslink density loss) and crosslinking recombination (network building) reactions. Apart from the crosslink structure stability, the presence of unsaturation along the polymer chain after vulcanization affects the high temperature activation energy.

The Slag Influence on High Temperature Resistance of Aluminophosphate Cementfor Heavy Oil Thermal Recovery

2014 ◽  
Vol 33 (4) ◽  
pp. 325-328 ◽  
Author(s):  
Zaoyuan Li ◽  
Yan Wang ◽  
Xiaowei Cheng ◽  
Xiaoyang Guo
Keyword(s):  
Compressive Strength ◽  
High Temperature ◽  
Low Temperature ◽  
Heavy Oil ◽  
Thermal Recovery ◽  
Temperature Resistance ◽  
High Temperature Resistance ◽  
Zonal Isolation ◽  
Cement Strength ◽  
Isolation Performance

AbstractThe sharp strength recession of silicate cement in high temperature is the crucial reason of casings damage and zonal isolation failure in heavy oil thermal recovery. Although aluminophosphate cement has a better high temperature resistance in comparison with silicate cement, its compressive strength recession in high temperature slightly recessed. The results show that adding slag into aluminophosphate cement can not only develop compressive strength of cement at low temperature, but it can also improve the high temperature resistance of the cement. After adding slag, the formation of C2ASH8 conduces to develop cement strength at low temperature, and C3AS2H2 conduces to high temperature resistance. To increase temperature resistance of aluminophosphate cement, C3ASH4 generation and Al(OH)3 decomposition should be avoided. Crystal structure of cement after high temperature is well developed with compactly and neatly arranged, allowing cement to maintain good mechanical properties to help protect the casing and improve zonal isolation performance.

Study on the Thermodynamics and Kinetics in the Combustion Reaction between Titanium and Boron Powders

2007 ◽  
Vol 351 ◽  
pp. 189-194 ◽  
Author(s):  
K. Wang ◽  
Zheng Yi Fu ◽  
Wei Min Wang ◽  
Yu Cheng Wang ◽  
H. Wang ◽  
...  
Keyword(s):  
Particle Size ◽  
High Temperature ◽  
Low Temperature ◽  
Experimental Analysis ◽  
Combustion Temperature ◽  
Raw Materials ◽  
Temperature Range ◽  
Thermodynamics And Kinetics ◽  
Diffusion Controlled ◽  
Calculated Activation

Combustion synthesis of titanium diboride(TiB2) from titanium(Ti) and boron(B) powders was studied by theoretical calculation and experimental analysis. In high temperature range or in low temperature range, the calculated activation energies are 140KJ/mol or 355KJ/mol respectively, which is described by a change from dissolution-precipitation controlled process to diffusion-controlled process. With the increase of particle size of the raw materials, combustion temperature and propagating rate will both reduce. The propagating rate decreases with the addition of diluents. Further increase of diluents may result in a stop of the combustion wave halfway or even a failure of ignition.

Thermogravimetric Analysis of Different Biomass Materials and the Primary Biomass Components

2012 ◽  
Vol 260-261 ◽  
pp. 187-191
Author(s):  
Ya Bo Li ◽  
Xu Ming Zhang ◽  
Lei Qiang Zhao ◽  
Qiang Lu ◽  
Chang Qing Dong
Keyword(s):  
Activation Energy ◽  
Thermogravimetric Analysis ◽  
Combustion Process ◽  
Nitrogen Atmosphere ◽  
Pyrolysis Kinetics ◽  
High Activation ◽  
High Activation Energy ◽  
Pyrolysis Characteristics ◽  
Biomass Components ◽  
Biomass Materials

Thermogravimetric analysis (TGA) was employed to study the pyrolysis and combustion characteristics of three primary biomass components (cellulose, xylan and lignin) and seven different biomass materials under both of nitrogen and air atmosphere. Based on the experimental results, the pyrolysis and combustion kinetics were calculated. The results indicated that the three primary biomass components exhibited different decomposition characteristics and pyrolysis kinetics. Xylan was the least thermal stable component, while the lignin would form much more solid residues than the cellulose and xylan under the nitrogen atmosphere. Moreover, the pyrolytic devolatilization process of the cellulose had high activation energy, so was the char combustion process of the lignin. The seven biomass materials showed similar pyrolysis characteristics, and poplar wood exhibited high activation energy values in both of pyrolysis and combustion processes.

Experimental Study on Combustion Characteristics of Three Biomass Components

2014 ◽  
Vol 953-954 ◽  
pp. 309-312
Author(s):  
Gui Qiu Su ◽  
Jian Yang ◽  
Hong Bo Lu
Keyword(s):  
Experimental Study ◽  
Weight Loss ◽  
High Temperature ◽  
Low Temperature ◽  
Combustion Process ◽  
Combustion Characteristics ◽  
Heating Rates ◽  
Biomass Components ◽  
Coke Combustion ◽  
Obvious Weight Loss

Experiments on combustion characteristics of cellulose, xylan and lignin have been done conducted on Pyris1 TGA thermograyimetric analyzer (PE/USA) at different heating rates. The results show that: combustion of cellulose was mainly concentrated in a low temperature range, xylan has two obvious weight loss peaks, while the lignin combustion mainly concentrated in a high temperature coke combustion process.

The mechanism of the Pinacol-Pinacone rearragement. VI. Low temperature kinetics

1957 ◽  
Vol 10 (2) ◽  
pp. 160 ◽  
Author(s):  
JF Duncan ◽  
KR Lynn
Keyword(s):  
Activation Energy ◽  
High Temperature ◽  
Low Temperature ◽  
Hydrogen Ion ◽  
Ion Concentration ◽  
Temperature Reaction ◽  
Hydrogen Ion Concentration ◽  
High Temperature Reaction ◽  
Stage Process ◽  
Low Temperature Kinetics

The low temperature rearrangement of pinacol to pinacone appears to be second order with respect to the hydrogen ion concentration. The activation energy is, however, similar to that of the high temperature reaction. This is interpreted as indicating that in the low temperature reaction the synartetic step is formed by a two stage process, through a stable intermediate, and each stage requires the participation of a hydrogen ion.

Some properties of flash-evaporated Ga1−xAsx films

1991 ◽  
Vol 69 (6) ◽  
pp. 738-742
Author(s):  
M. R. Harwood ◽  
D. E. Brodie
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Stoichiometric Ratio ◽  
Flash Evaporation ◽  
Glass Substrates ◽  
Seebeck Coefficients ◽  
Temperature Activation ◽  
Power Measurements ◽  
P Type ◽  
Excess Component

a-Ga1−xAsx films containing small GaAs crystallites were prepared by flash evaporation onto low-temperature glass substrates. The As content in the films was varied from 41 to 69 at.%. Thermoelectric power measurements indicate that Ga-rich films are n-type and As-rich films are p-type, but the Seebeck coefficients for samples near the stoichiometric ratio were too small to measure. The optical gaps vary with As content in a way that is consistent with the suggestion that the material appears to be an alloy of a-GaAs and the excess component. High-temperature activation energies place the Fermi level near midgap in all samples and this is in line with the suggestion that this class of materials tend to self compensate as the film grows.

Sign in / Sign up

Export Citation Format

Share Document