Metal Dusting Corrosion of 9Cr-1Mo Steel in Propane-Butane Gas Mixture

2009 ◽  
Vol 289-292 ◽  
pp. 477-483
Author(s):  
Zbigniew Grzesik ◽  
Marek Danielewski ◽  
Stanisław Mrowec
Keyword(s):  
Total Pressure ◽  
Petrochemical Industry ◽  
Diffusion Processes ◽  
Metal Dusting ◽  
Second Stage ◽  
Reaction Proceeds ◽  
Two Stages ◽  
Kinetics Of ◽  
Low Rate ◽  
Propane Butane

The kinetics and mechanism of metal dusting corrosion of 9Cr-1Mo steel, commonly used in CCR platforming units, have been studied as a function of temperature (773 – 1173 K) in propane-butane atmosphere, being the mixture of 70 vol. % of propane and 30 vol. % of butane with the total pressure equal 105 Pa. The kinetics of corrosion have been studied thermogravimetrically in the apparatus enabling the mass changes of corroded sample to be followed continuously with the accuracy of the order of 10-6 g. It has been found that metal dusting corrosion in this atmosphere, modeling in some way industrial environments in petrochemical industry, is complex and two-stages of linear kinetics may be distinguished. In the first stage, which may be considered as an incubation period, the reaction proceeds with rather low rate, which increases dramatically in the second stage, the beginning of which depends strongly on temperature. Linear course of reaction indicates that chemical reactions and not diffusion processes determine the rate of corrosion. This conclusion is confirmed by the fact, that the layer of corrosion products is not compact but considerably porous.

Rubberised fabric for fuel soft storage tanks*

2018 ◽  
Vol 45 (7) ◽  
pp. 322-324
Author(s):  
Yu.N. Rybakov ◽  
A.V. Dedov ◽  
D.S. Plokhoi ◽  
D.V. Kolotilin
Keyword(s):  
Diffusion Processes ◽  
Motor Fuel ◽  
Residual Monomer ◽  
Experimental Conditions ◽  
Second Stage ◽  
Before And After ◽  
Nitrile Rubbers ◽  
Two Stages ◽  
Kinetics Of

The kinetics of extraction of dibutyl sebacinate by different grades of motor fuel from rubberised fabric based on a blend of nitrile rubbers SKN-26M and SKN-40M was investigated. The kinetics was determined according to the GOST 9.030-74 standard from the change in weight of the specimen after holding in fuel at 50°C and drying. The change in quality of the fuel after contact with the fabric was recorded from the change in the content of existent gum in fuel according to GOST 1567-97 (ISO 6246-95) and its acidity according to GOST 5985-79 before and after contact with the rubberised fabric. It was shown that the process of extraction proceeds in two stages, the time of the first of which under experimental conditions is not dependent on the type of fuel. The rate of the first stage is much higher than the rate of the second stage. The relation of rates and proportion of extracted fuel at the first and second stages depends on the type of fuel. It can be asserted that the surplus amount of extracted substances is made up of impurities, which include residual monomer or its derivatives and substances used in the synthesis of the rubber. The mechanism of extraction with extractant counterflow into the vulcanisate and its dependence on the grade of petrol is proposed, based on allowance for the diffusion processes in the system.

In-Situ Study of Ti/TiN Stability under Nitrogen Anneal

1999 ◽  
Vol 564 ◽  
Author(s):  
P. W. DeHaven ◽  
K. P. Rodbell ◽  
L. Gignac
Keyword(s):  
Annealing Temperature ◽  
Time Range ◽  
Second Phase ◽  
Transformation Rate ◽  
Transformation Mechanism ◽  
Second Stage ◽  
Transmission Electron ◽  
Reaction Proceeds ◽  
Two Stages

AbstractThe effectiveness of a TiN capping layer to prevent the conversion of α-titantium to titanium nitride when annealed in a nitrogen ambient has been studied over the temperature range 300–700°C using in-situ high temperature diffraction and transmission electron microscopy. Over the time range of interest (four hours), no evidence of Ti reaction was observed at 300°C. At 450°C. nitrogen was found to diffuse into the Ti to form a Ti(N) solid solution. Above 500°C the titanium is transformed to a second phase: however this reaction follows two different kinetic paths, depending on the annealing temperature. Below 600°C. the reaction proceeds in two stages, with the first stage consisting of Ti(N) formation, and the second stage consisting of the conversion of the Ti(N) with a transformation mechanism characteristic of short range diffusion (grain edge nucleation). Above 600°C, a simple linear transformation rate is observed.

Kinetics of Mixed Low-Level Waste Incapsulation Using Iron Phosphate Chemically Bonded Cement

2006 ◽  
Vol 932 ◽  
Author(s):  
A.S. Aloy ◽  
T.I. Koltsova ◽  
E.N. Kovarskaya ◽  
M.Yu. Silin
Keyword(s):  
Formation Process ◽  
Iron Phosphate ◽  
Structural Formation ◽  
Low Level ◽  
Second Stage ◽  
Bivalent Iron ◽  
Acid Reaction ◽  
The Moment ◽  
Two Stages ◽  
Kinetics Of

ABSTRACTThe iron phosphate cement (IPC) structure formation process has been studied by Mossbauer spectroscopy. The IPC is formed as a result of interaction of iron oxides with orthophosphoric acid and could be used as a matrix for immobilization of low-level radioactive waste.The structural formation process has been shown may be considered to consist of two stages. The first stage lasts to the moment of setting, when the diffusion process goes on in the liquid phase. At this stage the main fragments of the structural polymeric frame of the IPC are developed consisting of iron (+2) and (+3) phosphates. The rate of the oxides-with-phosphoric-acid reaction as well as the time of hardening depends on the bivalent iron content.The second stage begins from the moment of setting when the diffusion becomes slower. At this stage the process is characterized by the negligible increase in the iron phosphates (+2), (+3) content and transformation of the previously formed phosphates.The nuclear gamma-resonance (NGR) parameters have been determined of FeH3(PO4)2·2.5H2O, forming in the hematite (Fe2O3) based IPC: isomeric shift (IS) = 0.46 mm/s, quadrupole splitting (QS) = 0.197 mm/s, FWHM =0.282 mm/s.

The kinetics of dehydration in Ca-montmorillonite: an in situ X-ray diffraction study

1998 ◽  
Vol 62 (5) ◽  
pp. 647-656 ◽  
Author(s):  
Helen J. Bray ◽  
Simon A. T. Redfern ◽  
Simon M. Clark
Keyword(s):  
Interlayer Spacing ◽  
X Ray Diffraction ◽  
Interlayer Water ◽  
X Ray ◽  
Shock Heating ◽  
Naturally Occurring ◽  
Reaction Proceeds ◽  
Two Stages ◽  
Kinetics Of

AbstractThe thermal dehydration of naturally occurring Ca-montmorillonite has been studied by in situ X-ray diffraction at temperatures between 60–120°C. The time-temperature-dependence of the position of the basal (001) reflection reveals that interlayer water loss on isothermal dehydration occurs in two stages. After an initial rapid decrease in interlayer spacing (on shock heating to an isothermal soak temperature) the reaction proceeds towards equilibrium more slowly. Furthermore, the width of the (001) reflection changes with time, reflecting transformation-dependent changes in homogeneity perpendicular to (001) with a maximum in peak width at the point where the rate of the reaction appears to change. This suggests that, as the interlayer spacing collapses, a local change is induced in the structure, affecting the means of movement of the water from the interlayer.

Oxidation Kinetics of the Sintered Iron Parts Steam Treated in an Industrial Continuous Furnace

2010 ◽  
Vol 660-661 ◽  
pp. 243-248
Author(s):  
Eduardo Nunes ◽  
Ivan Gilberto Sandoval Falleiros
Keyword(s):  
Oxidation Kinetics ◽  
Continuous Furnace ◽  
Steam Treatment ◽  
Sintered Iron ◽  
Second Stage ◽  
Parabolic Law ◽  
Controlling Mechanism ◽  
Iron Diffusion ◽  
Two Stages ◽  
Kinetics Of

It has been studied a steam treatment process in an industrial continuous furnace for sintered iron parts in a temperature range varying from 490 to 570 °C and sample´s sintered densities of 6,52 and 6,77 g / cm3 . The tests have showed oxidation kinetics with two stages, each of them obeying a parabolic law. The first stage was faster than the second. The oxidation time when the oxidation kinetics of the first stage has changed for the second stage showed off very sensitive to the process temperature and sintered densities of the parts which are in agreement with the process rate controlling mechanism that was found to be the iron diffusion through the oxide layer.

Kinetics of Mg2Sn Synthesis Reaction under Isothermal Condition

2010 ◽  
Vol 146-147 ◽  
pp. 1712-1716
Author(s):  
Yu Feng Wu ◽  
Wen Bo Du ◽  
Zhao Hui Wang ◽  
Tie Yong Zuo
Keyword(s):  
Isothermal Condition ◽  
Growth Control ◽  
Nucleation And Growth ◽  
Synthesis Process ◽  
Synthesis Reaction ◽  
Isothermal Reaction ◽  
Second Stage ◽  
Two Stages ◽  
Kinetics Of ◽  
Good Agreement

The kinetics of Mg2Sn synthesis reaction was studied under isothermal condition in the present paper. Results indicated that the isothermal reaction of Mg2Sn was controlled by two reactive mechanisms: the nucleation and growth control in the first stage corresponding to the Avrami exponent, m≈3, and the phase boundary control in the second stage corresponding to m≈1.1. The reactive activation energy (Ea ) for the two stages was 293.6 kJ·mol-1 and 358.1 kJ·mol-1, respectively. The microstructural evolution in Mg2Sn synthesis process was in good agreement with the two reactive mechanisms.

Kinetics of B2 and D03 Ordering: Theory

1990 ◽  
Vol 186 ◽  
Author(s):  
L. Anthony ◽  
B. Fultz
Keyword(s):  
Range Order ◽  
Rate Theory ◽  
Probability Method ◽  
Interatomic Potentials ◽  
Second Stage ◽  
Activated State ◽  
State Rate ◽  
Two Stages ◽  
Kinetics Of ◽  
Path Probability Method

AbstractMonte-Carlo simulations (MCS) and the path probability method (PPM) were used to study disorder→order transformations in bcc alloys having the AB3 stoichiometry. Both methods used an explicit vacancy mechanism of ordering and an activated-state rate theory for the vacancy jumps. We studied the evolution of short-range order (SRO) as well as B2 and D03 long-range order (LRO) in alloys that began as random solid solutions. The growth rates of SRO and LRO were significantly higher for the PPM than for the MCS. We attribute this difference to improper handling of correlated vacancy motions in the PPM. The PPM also suffered from an artificial incubation time for the initiation of LRO. Both the MCS and the PPM showed that SRO has a tendency to develop in two stages. In the first stage there is a quick relaxation of the SRO by itself. In the second stage, which occurs with a longer time constant, the SRO and LRO grow simultaneously. Parametric plots of one order parameter against another, here termed “kinetic paths”, are discussed. A variety of different kinetic paths through the B2 and D03 order parameters can be predicted theoretically, depending on the choice of interatomic potentials. This range of calculated kinetic paths is broad enough to encompass our experimental results of SRO and LRO evolution in Fe3Al.

THERMODYNAMIC AND ELECTROCHEMICAL STUDY OF VANADIUM SOLUTIONS: TOWARDS VANADIUM RECOVERY FROM A SPENT CATALYST

2021 ◽  
Author(s):  
René Antaño-López ◽  
Fidel Hernández-Pérez ◽  
Fabricio Espejel-Ayala
Keyword(s):  
Petrochemical Industry ◽  
Large Scale ◽  
Industrial Wastes ◽  
Electrochemical Study ◽  
Spent Catalyst ◽  
Second Stage ◽  
Reduction Potentials ◽  
Electrochemical Processes ◽  
Thermochemical Processes ◽  
Two Stages

Due to the low abundance of vanadium in nature (about 135 g/t), the feasibility to recover it from industrial wastes has highly attracted scientific and technological attention. The main recovery routes reported are associated with chemical or thermochemical processes. However, the electrochemical recovery of vanadium from industrial wastes has been poorly investigated. In this work, a thermodynamic and electrochemical study for the possible vanadium recovery from a spent catalyst generated in the petrochemical industry was conducted. The study was divided into two stages using low vanadium concentrations. In the first stage, the recovery of vanadium was possible in its V4+ state at low reduction potentials, whereas for the second stage, cyclic voltammetry was used to calculate the diffusion coefficient and the heterogeneous velocity coefficient of the V5+/V4+ redox pair. The obtained values are similar to those reported in the literature for aqueous solutions at high vanadium concentrations and would allow the design of the system at large scale. This report aims to set the conditions for the possible vanadium recovery from a spent catalyst by means of electrochemical processes, although the optimization of such conditions must be further explored.

scholarly journals Studies of precipitation during the decomposition process of phosphorus-containing compounds

2019 ◽  
Vol 80 (4) ◽  
pp. 312-315
Author(s):  
M. M. Ganbarov ◽  
M. M. Ataev ◽  
K. K. Gazvini
Keyword(s):  
Raw Materials ◽  
Environmentally Friendly ◽  
Decomposition Process ◽  
Second Stage ◽  
Phosphorus Containing ◽  
Neutralization Process ◽  
The Absolute ◽  
Two Stages ◽  
Kinetics Of

The kinetics of the process of using phosphorus-containing mineral compounds by their decomposition, which are actual problems, has been studied. At beginning of the it have been notified that the process takes place in two stages. These stages of the process are differed from each another mainly by rate of process realization, because a rate of the first stage is much more that a rate of the second stage. This fact is a reason of the deep research of kinetic of given process. Apart from that a detailed study of these processes connect with some problems of enter prices. All these question are analizied in the work, also the information by methodical carry out of experiments. Regime parameters correlation of components, concentrations of components, a time requite for realization of process are presented. The dependence of degree by different mass correlation of components from the time realization of process are also shown. In the work the types existence of precipitate, monitite brush it are shown. On base of received date a dissolubility of the base received product are graphically presented. In the work an influence of mass correlation of CaO?P2O5 and time of process realization on precipitation is studied. It have been determined that by 650C temperature a mass correlation of the base components must be equal to one, by that a time being used on neutralization process don’t play the practical role, because its increase and decrease don’t influence practically on process indices. The results shown that by equality of components CO?P2O5=1 correlation during four hours the precipitation degree makes up to 90,66 % and during 1 hour this index is 78,2 % for duringthe remaining three during this index is increased on 12 %. By using of these received data these is a possibility determination of the optimum technological conditions for given process. it is shown that there are opportunities to achieve processivization, to increase the use of raw materials and to obtain an environmentally friendly product with the introduction of regime parameters and component ratios in the absolute state.

Decomposition of BrO studied by kinetic spectroscopy

1970 ◽  
Vol 48 (22) ◽  
pp. 3487-3490 ◽  
Author(s):  
J. Brown ◽  
George Burns
Keyword(s):  
Activation Energy ◽  
Total Pressure ◽  
Reaction Rate ◽  
Second Order ◽  
Kcal Mole ◽  
Kinetic Spectroscopy ◽  
Reaction Proceeds ◽  
One Step ◽  
Kinetics Of ◽  
Activated Complex

Kinetics of BrO decomposition was studied between 293 and 673 °K using the technique of kinetic spectroscopy. At 293 °K the reaction rate is second order with respect to BrO and is independent of [Br2], [O2], and total pressure of diluent gas. The activation energy for decomposition obtained from rate measurements between 293 and 450 °K is 0.65 ± 0.05 kcal/mole. Above 450 °K this activation energy appears to increase to 4.5 kcal/mole. It is shown that, although kinetically the ClO and BrO decompositions are similar, the mechanism for BrO decomposition below 450 °K is much simpler than that of ClO. The reaction proceeds, most likely, via one step: 2 BrO → 2 Br + O2, with Br2O2 being an activated complex, which has either linear or staggered configuration. ClO and BrO decomposition is compared with [Formula: see text] reaction.

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