A comprehensive reaction scheme for the dehydrogenation and hydrogenolysis of n-butane, 1-butene and isobutane over supported ruthenium at high temperature

1975 ◽  
Vol 2 (1-2) ◽  
pp. 135-142 ◽  
Author(s):  
V. Ragaini ◽  
A. Spadaro ◽  
G. Cum
Keyword(s):  
High Temperature ◽  
Reaction Scheme

The gaseous oxidation of acetone - I. The high-temperature reaction

1964 ◽  
Vol 279 (1377) ◽  
pp. 236-247 ◽  
Keyword(s):  
High Temperature ◽  
Temperature Region ◽  
Reaction Scheme ◽  
Temperature Reaction ◽  
High Temperature Region ◽  
Chain Branching ◽  
High Temperature Reaction ◽  
Rate Of Reaction

The gaseous oxidation of acetone has been studied at temperatures between 250 and 510°C at pressures up to 450 mmHg. In contrast to earlier reports, two oxidation régimes have been discovered, separated by a region where the rate of reaction decreases as the temperature rises. This paper presents the results of a detailed study of the kinetics and products of the reaction in the high-temperature region. The reaction is autocatalytic, and a reaction scheme is proposed which accounts for the principal experimental facts. This scheme involves degenerate chain branching, in which the oxidation of formaldehyde plays an important part.

Modeling and Design of a High Temperature Chamber Fed by a Plasma Torch for Removal of Tars

2012 ◽  
Author(s):  
Romain Demarthon ◽  
Frédéric Marias ◽  
Alice Fourcault ◽  
Jean Paul Robert-Arnouil
Keyword(s):  
High Temperature ◽  
Fixed Bed ◽  
Pilot Scale ◽  
Waste Recycling ◽  
Reaction Scheme ◽  
Thermochemical Conversion ◽  
Condensation Temperature ◽  
Reactor Performance ◽  
Gas Treatment ◽  
Discrete Phase

One way of biomass and/or waste recycling is its thermochemical conversion into combustible gas. Mainly composed of CO,H2 and CH4, the gas may also contain varying amounts of impurities (dust, polluting products, tar or soot). Specifically, there is a tar problem: their high condensation temperature is incompatible with an industrial utilization. They can cause rapid fouling, corrosion and abrasion into turbines or engines. Proposed by EUROPLASMA, the CHO-Power process aims to generate electricity from a mixture of municipal waste and biomass using a fixed bed gasifier with conventional gas treatment. Its specificity consists of an unit called Turboplasma. This stage allows to reach very high temperature in order to obtain temperature around 1600K, and so to degrade all tars present, even heavier. Indeed, EUROPLASMA built a gasification pilot unit based on fluidized bed technology, (called KIWI) to qualify the synthesis gas produced. TURBOPLASMA pilot scale will be installed there. The objective of this work is the design of this high temperature stage thanks to numerical modeling. Reaction scheme used previously [4] to modelize tar degradation in the Turboplasma of CHO-Power, has been improved: a discrete phase modeling has been added providing a better view of the TURBOPLASMA internal behavior. Indeed, char particles from syngas can significantly change the reactor performance. This study shows that char particles react primarily with the H2O and CO2. Char gasification takes place in areas of high velocity and temperature gradient. Increased understanding of aerodynamics inside the reactor allows a better estimate of the overall performance of the reactor. Performance evaluation of the reactor is based on a set of parameters such as levels of heat loss, velocity gradient, mixing quality, residence time.

Influence of Thermo-Mechanical Processing on the Microstructure of Beryllia Dispersed Nickel Alloys

1973 ◽  
Vol 31 ◽  
pp. 184-185
Author(s):  
M.S. Grewal ◽  
S.A. Sastri ◽  
N.J. Grant
Keyword(s):  
High Temperature ◽  
Nickel Alloys ◽  
Thermomechanical Processing ◽  
Cold Work ◽  
High Temperature Strength ◽  
Strengthening Effect ◽  
Mechanical Processing ◽  
Uniform Dispersion ◽  
Oxide Particles ◽  
Nickel Base

Currently there is a great interest in developing nickel base alloys with fine and uniform dispersion of stable oxide particles, for high temperature applications. It is well known that the high temperature strength and stability of an oxide dispersed alloy can be greatly improved by appropriate thermomechanical processing, but the mechanism of this strengthening effect is not well understood. This investigation was undertaken to study the dislocation substructures formed in beryllia dispersed nickel alloys as a function of cold work both with and without intermediate anneals. Two alloys, one Ni-lv/oBeo and other Ni-4.5Mo-30Co-2v/oBeo were investigated. The influence of the substructures produced by Thermo-Mechanical Processing (TMP) on the high temperature creep properties of these alloys was also evaluated.

Application of TEM to Deformation, Wear, and Fracture of Ceramics

1974 ◽  
Vol 32 ◽  
pp. 472-473
Author(s):  
B. J. Hockey
Keyword(s):  
Wear Resistance ◽  
High Temperature ◽  
Mechanical Behavior ◽  
Brittle Materials ◽  
High Temperature Strength ◽  
Wide Range ◽  
Corrosive Environments ◽  
Further Development

Ceramics, such as Al2O3 and SiC have numerous current and potential uses in applications where high temperature strength, hardness, and wear resistance are required often in corrosive environments. These materials are, however, highly anisotropic and brittle, so that their mechanical behavior is often unpredictable. The further development of these materials will require a better understanding of the basic mechanisms controlling deformation, wear, and fracture.The purpose of this talk is to describe applications of TEM to the study of the deformation, wear, and fracture of Al2O3. Similar studies are currently being conducted on SiC and the techniques involved should be applicable to a wide range of hard, brittle materials.

Lattice Imaging of Grain Boundaries in Ceramics

1977 ◽  
Vol 35 ◽  
pp. 114-115
Author(s):  
D. R. Clarke ◽  
G. Thomas
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Silicon Nitride ◽  
Grain Boundaries ◽  
High Temperature Strength ◽  
Current Interest ◽  
Lattice Imaging ◽  
Special Significance ◽  
Structural Applications ◽  
Refractory Ceramics

Grain boundaries have long held a special significance to ceramicists. In part, this has been because it has been impossible until now to actually observe the boundaries themselves. Just as important, however, is the fact that the grain boundaries and their environs have a determing influence on both the mechanisms by which powder compaction occurs during fabrication, and on the overall mechanical properties of the material. One area where the grain boundary plays a particularly important role is in the high temperature strength of hot-pressed ceramics. This is a subject of current interest as extensive efforts are being made to develop ceramics, such as silicon nitride alloys, for high temperature structural applications. In this presentation we describe how the techniques of lattice fringe imaging have made it possible to study the grain boundaries in a number of refractory ceramics, and illustrate some of the findings.

Effect of Improved ThO2 Particle Dispersion in Nickel on High-Temperature Strength

1970 ◽  
Vol 28 ◽  
pp. 444-445
Author(s):  
E. R. Kimmel ◽  
H. L. Anthony ◽  
W. Scheithauer
Keyword(s):  
High Temperature ◽  
Metal Matrix ◽  
Oxide Particle ◽  
Oxide Phase ◽  
Dislocation Motion ◽  
Particle Dispersion ◽  
High Temperature Strength ◽  
Strengthening Effect ◽  
Oxide Particles ◽  
The Stability

The strengthening effect at high temperature produced by a dispersed oxide phase in a metal matrix is seemingly dependent on at least two major contributors: oxide particle size and spatial distribution, and stability of the worked microstructure. These two are strongly interrelated. The stability of the microstructure is produced by polygonization of the worked structure forming low angle cell boundaries which become anchored by the dispersed oxide particles. The effect of the particles on strength is therefore twofold, in that they stabilize the worked microstructure and also hinder dislocation motion during loading.

The Ordered Phase Formation in Ti-Al-Ga Alloys

1970 ◽  
Vol 28 ◽  
pp. 440-441
Author(s):  
Shiro Fujishiro ◽  
Harold L. Gegel
Keyword(s):  
Thermal Stability ◽  
High Temperature ◽  
Titanium Alloys ◽  
Growth Kinetics ◽  
Stoichiometric Composition ◽  
Good Potential ◽  
Alpha Titanium ◽  
Cold Rolled ◽  
Kinetics Of ◽  
Thermal Stability Of

Ordered-alpha titanium alloys having a DO19 type structure have good potential for high temperature (600°C) applications, due to the thermal stability of the ordered phase and the inherent resistance to recrystallization of these alloys. Five different Ti-Al-Ga alloys consisting of equal atomic percents of aluminum and gallium solute additions up to the stoichiometric composition, Ti3(Al, Ga), were used to study the growth kinetics of the ordered phase and the nature of its interface.The alloys were homogenized in the beta region in a vacuum of about 5×10-7 torr, furnace cooled; reheated in air to 50°C below the alpha transus for hot working. The alloys were subsequently acid cleaned, annealed in vacuo, and cold rolled to about. 050 inch prior to additional homogenization

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