Kinetics of Carbon Gasification by Steam. Effect of High Temperature Pretreatment on Reactivity of Low Temperature Char to Steam and Carbon Dioxide

AbstractFlue-cured Virginia tobacco has been heated in nitrogen and nitrogen/oxygen mixtures under flow conditions, and the rate of formation of carbon monoxide and carbon dioxide has been determined as a function of temperature, heating rate, and proportion of oxygen in the gas. When the tobacco is heated in nitrogen at heating rates comparable to those in a smouldering cigarette, 27 % of the carbon content of the tobacco is converted to carbon oxides. Both carbon oxides show two distinct formation regions: a low-temperature region (about 100°-450°C), and a high-temperature region (about 550°-900°C). These temperature limits are almost identical to those predicted from studies on the combustion coal of a cigarette burning in air. When tobacco, or the carbonaceous residue remaining after the pyrolysis experiments, is heated in nitrogen / oxygen mixtures, the total amount of carbon converted to carbon monoxide and carbon dioxide is independent of heating rate, but the relative proportions of the two oxides are strongly dependent on heating rate. At the lower heating rate, proportionally less carbon monoxide, and more carbon dioxide, is produced. Under oxidation conditions, about 70 % of both carbon oxides formed in the low-temperature region (100°-450°C) are produced by tobacco decomposition reactions, whereas in the high-temperature region about 10-20 % of the carbon monoxide, and 2-9 % of the carbon dioxide, are produced by tobacco decomposition.

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Effect of Low-Temperature Recovery Treatments on Subsequent Recrystallization in Al-2.5%Mg

Materials Science Forum ◽

10.4028/www.scientific.net/msf.550.381 ◽

2007 ◽

Vol 550 ◽

pp. 381-386 ◽

Cited By ~ 11

Author(s):

B. Decreus ◽

Hatem S. Zurob ◽

John Dunlop ◽

Yves Bréchet

Keyword(s):

High Temperature ◽

Low Temperature ◽

Hardness Measurement ◽

Optical Metallography ◽

Mg Alloys ◽

High Temperature Annealing ◽

Recrystallization Kinetics ◽

Temperature Recovery ◽

Kinetics Of ◽

And Calorimetry

The effect of low temperature recovery treatments on the recrystallization kinetics during subsequent high temperature annealing was investigated in three Al-2.5%Mg alloys with various Fe additions. Recovery treatments were carried out at 190oC for times ranging from 0.25 to 65 hrs. Recrystallization treatments were carried out at 280oC. The kinetics of recrystallization was followed using the techniques of hardness measurement, optical metallography and calorimetry.

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Kinetika Pengeringan Cabai dengan Perlakuan Blansing Suhu Rendah-Waktu Lama

AGRITEKNO Jurnal Teknologi Pertanian ◽

10.30598/jagritekno.2021.10.1.24 ◽

2021 ◽

Vol 10 (1) ◽

pp. 24-35

Author(s):

Andi Muhammad Irfan ◽

Nunik Lestari ◽

Arimansyah Arimansyah ◽

A Ramli Rasyid

Keyword(s):

High Temperature ◽

Low Temperature ◽

Drying Rate ◽

Suitable Model ◽

Drying Time ◽

Drying Characteristics ◽

High Temperature Short Time ◽

Long Time ◽

Short Time ◽

Kinetics Of

This study was aimed to determine the drying kinetics of chilies that have been pretreated with low temperature long time (LTLT) blanching. Drying chilies with LTLT blanching pretreatment at 60, 70, and 80 oC for 20 minutes was assigned as treatment in this research. Drying chillies with high temperature short time (HTST) blanching pretreatment, without blanching pretreatment in the dryer, and without blanching pretreatment in direct sunlight were also studied as the comparison. The results showed that chilies treated with blanching pretreatment, both LTLT and HTST, have a faster drying rate and achieve the target moisture content faster than chilies that were not blanched. The color of dried chilies that were dried in a dryer was also better than dried chilies that were dried in the sun. Of all the blanching treatments, chilies with LTLT blanching pretreatment at 80 oC for 20 minutes had the fastest drying rate, a drying time of 34 hours, and the attractive dried chilli color. The evaluation results also showed that the Page model was the most suitable model to describe the drying characteristics of chilies with LTLT pretreatment blanching, with R2 ranging from 0.9913-0.9935, X2 ranging from 0.0005-0.0009, and RSME ranging from 0.0221-0.0293. Keywords: Chili; blanching; color; drying; mathematical model ABSTRAK Penelitian ini bertujuan untuk mengetahui kinetika pengeringan cabai yang diberi perlakuan awal low temperature long time (LTLT) blanching atau blansing pada suhu rendah dalam waktu yang relatif lama. Perlakuan pada penelitian ini yaitu pengeringan cabai dengan blansing metode LTLT pada suhu 60o, 70o, dan 80oC selama 20 menit. Sebagai pembanding, dilakukan juga pengeringan dengan perlakuan awal metode high temperature short time (HTST) blanching, pengeringan cabai tanpa perlakuan awal blansing di dalam alat pengering, serta pengeringan cabai tanpa perlakuan awal blansing di bawah sinar matahari secara langsung. Hasil penelitian menunjukkan bahwa cabai dengan perlakuan awal blansing, baik blansing metode LTLT maupun HTST, memiliki laju pengeringan yang lebih tinggi sehingga lebih cepat mencapai kadar air target dibandingkan dengan cabai tanpa perlakuan blansing. Warna cabai kering yang dihasilkan pada alat pengering juga lebih baik dari cabai kering yang dikeringkan langsung di bawah sinar matahari. Dari seluruh perlakuan yang melibatkan proses blansing, cabai dengan blansing metode LTLT pada suhu 80oC selama 20 menit merupakan perlakuan dengan laju pengeringan tercepat, dengan waktu pengeringan selama 34 jam, dan warna produk cabai kering yang menarik. Hasil evaluasi juga menunjukkan bahwa model Page adalah model yang paling sesuai untuk menggambarkan karakteristik pengeringan cabai dengan perlakuan awal blansing metode LTLT, dengan R2 berkisar antara 0.9913-0.9935, X2 berkisar antara 0.0005-0.0009, dan RSME berkisar antara 0.0221-0.0293. Kata kunci: Blansing; cabai; model matematika; pengeringan; warna

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Low Temperature Deformation Kinetics of Ruthenium Aluminide Alloys

MRS Proceedings ◽

10.1557/proc-552-kk7.11.1 ◽

1998 ◽

Vol 552 ◽

Cited By ~ 3

Author(s):

D. C. Lu ◽

T. M. Pollock

Keyword(s):

High Temperature ◽

Low Temperature ◽

Strain Rate ◽

Rate Change ◽

The Other ◽

Temperature Deformation ◽

Strain Rate Change ◽

Deformation Kinetics ◽

Ruthenium Aluminide ◽

Kinetics Of

ABSTRACTThe kinetics of low temperature deformation were investigated in several different polycrystalline RuAl alloys with the use of strain rate change experiments at 77 K and 298 K. Compositions investigated include RuAl, RuAl+0.5%B, Ru51.5 A48.5, Ru52 Al48, RU53 A147+0.5%B, Ru54.5 Al45.5, and Ru52 Al43 Sc5. Flow stresses did not vary substantially with temperature between 77 K and 298 K. Rate sensitivities were low compared to other B2 compounds and similar in all compositions investigated. Analyses of dislocation substructures after low strain deformation were conducted. The deformation kinetics and substructural observations suggest a higher intrinsic deformability for RuAI alloys with respect to the other high temperature B2 aluminides.

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Kinetics of high-temperature carbon gasification reaction

AIChE Journal ◽

10.1002/aic.690280211 ◽

1982 ◽

Vol 28 (2) ◽

pp. 237-244 ◽

Cited By ~ 6

Author(s):

N. J. Desai ◽

R. T. Yang

Keyword(s):

High Temperature ◽

Carbon Gasification ◽

Gasification Reaction ◽

Kinetics Of

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Corrosion Behavior and Mechanism of Heat-Resistant Steel T91 in High-Temperature Carbon Dioxide Environment

Materials Science Forum ◽

10.4028/www.scientific.net/msf.944.398 ◽

2019 ◽

Vol 944 ◽

pp. 398-403

Author(s):

Yong Gui ◽

Zhi Yuan Liang ◽

Miao Yu ◽

Qin Xin Zhao

Keyword(s):

Carbon Dioxide ◽

High Temperature ◽

Corrosion Behavior ◽

Optical Emission ◽

Emission Spectrometry ◽

X Ray Diffraction ◽

Heat Resistant Steel ◽

Scale Thickness ◽

Corrosion Scale ◽

Kinetics Of

Corrosion behavior of martensitic heat resisting steel T91 in high-temperature carbon dioxide environment at 500-700 °C was investigated. X-ray diffraction, scanning electron microscopy and glow-discharge optical emission spectrometry were employed to characterize the corrosion products. The results showed that the corrosion kinetics of T91 followed a parabolic law with experimental time. The oxide scale thickness of T91 followed an exponential growth law from 500 °C to 700 °C. Internal carburization was detected underneath the corrosion scale. What’s more, the carburization depth was larger than the corrosion scale. The variations of Cr and C elements distribution were discussed.

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Properties of Mg2NiH4 at 450-570 K

MRS Proceedings ◽

10.1557/proc-513-93 ◽

1998 ◽

Vol 513 ◽

Cited By ~ 7

Author(s):

S. E. Guthrie ◽

G. J. Thomas ◽

D. Noreus ◽

E. Ronnebro

Keyword(s):

High Temperature ◽

Low Temperature ◽

Thermal Stresses ◽

Microscopic Analysis ◽

Hydrogen Desorption ◽

High Temperature Phase ◽

Desorption Kinetics ◽

Temperature Phase ◽

Monoclinic Distortion ◽

Kinetics Of

ABSTRACTIt has been established that Mg2NiH4 undergoes a phase change around 500°K in which the orientation of the NiH4 complex is quenched in a monoclinic distortion of the cubic high temperature phase. This results in the formation of domains in which the lattice distortion is accommodated by microtwinning. These effects can be absent when the hydride phase is formed below the transition temperature. Microscopic analysis verifies a similar basal cubic structure in the low temperature phase; however, the domains and microtwins are absent in this material and it can readily be destabilized by thermal stresses induced by the electron beam. It is of interest to measure and compare the effect of the lattice differences on the thermodynamic properties of the low temperature versus the high temperature hydride phases. We report the equilibrium PCT data and hydrogen desorption kinetics of the two hydrides in the temperature range of 450–570 K.

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