scholarly journals Influence of Pyrolysis Gas on Volatile Yield and CO2 Reaction Kinetics of the Char Samples Generated in a High-Pressure, High-Temperature Flow Reactor

Energies ◽  
2018 ◽  
Vol 12 (1) ◽  
pp. 107 ◽  
Author(s):  
Vijayaragavan Krishnamoorthy ◽  
Yaw Yeboah ◽  
Sarma Pisupati
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
Reaction Kinetics ◽  
Flow Reactor ◽  
Structural Characteristics ◽  
Exponential Factor ◽  
Volatile Yield ◽  
High Pressure High Temperature ◽  
N2 Atmosphere ◽  
Significant Difference

The influence of pyrolysis atmosphere on volatile yield, structural characteristics, and CO2 reaction kinetics have been examined on chars generated from Pittsburgh No. 8 coal at 6.2 bar pressure and 1100 °C in a high-pressure, high-temperature flow reactor (HPHTFR) in Ar, N2, 50 (vol. %) CO2 and N2 (i.e., CO2/ N2) atmospheres. The chars were characterized for volatile yield, thermal swelling ratio, surface area, pore size distribution, crystallite structure, defects to graphitic intensity ratio, and char-CO2 reactivity. Coal pyrolyzed in CO2/N2 showed higher volatile yield (27%) compared to coal pyrolyzed in argon (~16%) and nitrogen (~19%). Except for volatile yield, there was no significant difference in structural properties for chars generated in different pyrolysis atmospheres. The difference in volatile yield was found to be due to presence of unconverted tetrahydrofuran (THF) soluble tar/soot. The results also showed that the intrinsic reactivity was highest for char generated in N2 atmosphere and lowest for char generated in CO2/N2 atmosphere. The kinetic parameters (activation energy and pre-exponential factor) for the char-CO2 reaction were ascertained using nth order model. The activation energies did not differ significantly among the chars generated in different pyrolysis atmospheres. The order of reaction was found to follow: CO2/N2 char > N2 char ≈ Ar char.

scholarly journals Effect of Temperature, Pressure, Feed Particle Size, and Feed Particle Density on Structural Characteristics and Reactivity of Chars Generated during Gasification of Pittsburgh No.8 Coal in a High-Pressure, High-Temperature Flow Reactor

Energies ◽  
2019 ◽  
Vol 12 (24) ◽  
pp. 4773
Author(s):  
Vijayaragavan Krishnamoorthy ◽  
Sarma V. Pisupati
Keyword(s):  
Particle Size ◽  
High Pressure ◽  
High Temperature ◽  
Flow Reactor ◽  
Particle Density ◽  
Structural Characteristics ◽  
Swelling Ratio ◽  
Group I ◽  
High Pressure High Temperature ◽  
Intrinsic Reactivity

The gasification behavior of coal under high-temperature and high-pressure conditions is important from the perspective of designing and optimizing high efficiency gasifiers and troubleshooting existing gasifiers. The effect of feed particle size, density, temperature, and pressure on char porous structure, morphology, reflectance, and reactivity under conditions relevant to entrained-flow gasification was investigated. The chars were generated over a range of temperatures (1100, 1300, and 1400 °C at 11.3 bar for the −150 + 106 µm fraction), pressures (3.4, 6.2, 11.3, 15.5, and 21.7 bar at 1300 °C for the −150 + 106 µm fraction), for various size fractions (−106 + 75, −150 + 106, −212 + 150, −420 + 212 µm at 1300 °C and 11.3 bar), and density fractions (<1.3, 1.3–1.6, >1.6g/cc for the −106 + 75 µm at 1300 °C and 11.3 bar) of Pittsburgh No.8 bituminous coal using a high-pressure, high-temperature flow reactor (HPHTFR) in a equimolar mixture of CO2 and N2. Chars were characterized for conversion, morphology, thermal swelling ratio, and reactivity using ash tracer technique, oil immersion microscopy, tap density technique, and a thermogravimetric analyzer, respectively, and the results were statistically analyzed to determine for effects by feed particle density, feed particle size, temperature, and pressure. The results showed that the conversion was most affected by temperature, followed by feed particle size, pressure, and feed particle density. In the case of structural characteristics (i.e., thermal swelling ratio and group-I char concentration), feed particle density affected group-I concentration, while both feed particle size and feed particle density affected thermal swelling ratio. Variation in vitrinite content and fragmentation affected the thermal swelling ratio and group-I char concentration. In the case of intrinsic reactivity, particle density showed the largest effect, followed by temperature, particle size, and pressure. An increase in reflectance and temperature was found to inversely affect intrinsic reactivity.

The high-pressure cadmium borate Cd6B22O39·H2O

2015 ◽  
Vol 70 (3) ◽  
pp. 183-190 ◽  
Author(s):  
Gerhard Sohr ◽  
Nina Ciaghi ◽  
Klaus Wurst ◽  
Hubert Huppertz
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
Structural Characteristics ◽  
X Ray Diffraction ◽  
X Ray ◽  
High Pressure High Temperature ◽  
Cell Dimensions ◽  
Temperature Experiment ◽  
Unit Cell Dimensions ◽  
Ir And Raman

AbstractSingle crystals of the hydrous cadmium borate Cd6B22O39·H2O were obtained through a high-pressure/high-temperature experiment at 4.7 GPa and 1000 °C using a Walker-type multianvil apparatus. CdO and partially hydrolyzed B2O3 were used as starting materials. A single crystal X-ray diffraction study has revealed that the structure of Cd6B22O39·H2O is similar to that of the type M6B22O39·H2O (M=Fe, Co). Layers of corner-sharing BO4 groups are interconnected by BO3 groups to form channels containing the metal cations, which are six- and eight-fold coordinated by oxygen atoms. The compound crystallizes in the space group Pnma (no. 62) [R1=0.0379, wR2=0.0552 (all data)] with the unit cell dimensions a=1837.79(5), b=777.92(2), c=819.08(3) pm, and V=1171.00(6) Å3. The IR and Raman spectra reflect the structural characteristics of Cd6B22O39·H2O.

scholarly journals Intrinsic gasification kinetics of coal chars generated in a high-pressure, high-temperature flow reactor

2019 ◽  
Vol 375 ◽  
pp. 122028 ◽  
Author(s):  
Vijayaragavan Krishnamoorthy ◽  
Nandakumar Krishnamurthy ◽  
Sarma V. Pisupati
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
Flow Reactor ◽  
High Pressure High Temperature ◽  
Kinetics Of

scholarly journals High-pressure synthesis and crystal structure of the mixed-cation borate Ga4In4B15O33(OH)3

2019 ◽  
Vol 74 (4) ◽  
pp. 357-363
Author(s):  
Daniela Vitzthum ◽  
Hubert Huppertz
Keyword(s):  
Crystal Structure ◽  
High Pressure ◽  
High Temperature ◽  
Diffraction Data ◽  
X Ray Diffraction ◽  
Synthesis And Crystal Structure ◽  
X Ray ◽  
Mixed Cation ◽  
High Pressure High Temperature ◽  
Pressure Synthesis

AbstractThe mixed cation triel borate Ga4In4B15O33(OH)3 was synthesized in a Walker-type multianvil apparatus at high-pressure/high-temperature conditions of 12.5 GPa and 1300°C. Although the product could not be reproduced in further experiments, its crystal structure could be reliably determined via single-crystal X-ray diffraction data. Ga4In4B15O33(OH)3 crystallizes in the tetragonal space group I41/a (origin choice 2) with the lattice parameters a = 11.382(2), c = 15.244(2) Å, and V = 1974.9(4) Å3. The structure of the quaternary triel borate consists of a complex network of BO4 tetrahedra, edge-sharing InO6 octahedra in dinuclear units, and very dense edge-sharing GaO6 octahedra in tetranuclear units.

Iodine-mediated high-pressure high-temperature carbonization of hydrocarbons and synthesis of nanodiamonds

2021 ◽  
Vol 137 ◽  
pp. 111189
Author(s):  
E.A. Ekimov ◽  
K.M. Kondrina ◽  
I.P. Zibrov ◽  
S.G. Lyapin ◽  
M.V. Lovygin ◽  
...  
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
High Pressure High Temperature
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