The Effect of Gas Flow Rate on the Oxide Scale Morphology of a 10%Cr-Ferritic Steels in Ar-H2O and Ar-H2-H2O Mixtures

2006 ◽  
Vol 522-523 ◽  
pp. 155-162 ◽  
Author(s):  
J. Zurek ◽  
M. Michalik ◽  
Lorenz Singheiser ◽  
W.Joe Quadakkers
Keyword(s):  
Oxide Scale ◽  
Water Vapour ◽  
Flow Rate ◽  
Gas Flow ◽  
Oxidation Process ◽  
Oxidation Behaviour ◽  
Gas Flow Rate ◽  
Flow Conditions ◽  
Water Vapour Content ◽  
Equilibrium Oxygen

The oxidation behaviour of a Ferritic 10%Cr steel in Ar-H2O mixtures was investigated at 650°C. The studies aimed at elucidating the effect of water vapour content as well as the gas flow rate on the mechanisms of oxide scale formation. An important observation of the present investigation is, that H2 produced by the reaction of water vapour with the steel, can play a significant role in the oxidation process. It affects the possibility to form an external haematite layer and may alter the oxide scale growth rate. The extend by which the H2 affects the oxidation behaviour depends on the gas flow conditions, the water vapour content and the exposure time. To confirm these observations a number of specimens were oxidized in Ar-H2-H2O mixtures. This atmosphere guarantees a very low equilibrium oxygen partial pressure, in which H2 formed by reaction of the gas with the metal, does not substantially alter the thermodynamic properties of the gas.

Effect of gas flow rate on oxidation behaviour of alloy 625 in wet air in the temperature range 900-1000 °C

2016 ◽  
Vol 68 (2) ◽  
pp. 159-170 ◽  
Author(s):  
P. Huczkowski ◽  
W. Lehnert ◽  
H.-H. Angermann ◽  
A. Chyrkin ◽  
R. Pillai ◽  
...  
Keyword(s):  
Flow Rate ◽  
Gas Flow ◽  
Oxidation Behaviour ◽  
Gas Flow Rate ◽  
Alloy 625 ◽  
Temperature Range

Microstructures and Hardness of Silver Alloys after Internal Oxidation Process

2011 ◽  
Vol 194-196 ◽  
pp. 1217-1220
Author(s):  
Kessaraporn Wathanyu ◽  
Siriporn Rojananan
Keyword(s):  
Internal Oxidation ◽  
Flow Rate ◽  
Gas Flow ◽  
Vickers Microhardness ◽  
Oxidation Process ◽  
Dendritic Structure ◽  
Gas Flow Rate ◽  
Silver Alloys ◽  
Oxygen Gas ◽  
Equiaxed Grains

The aim of this paper is to study the microstructures and hardness of silver alloys after internal oxidation process. The Ag-5Sn and Ag-5Cu alloys were prepared by melting and cast into ingots and then they were internal oxidized at the temperature range from 550 to 750°C, for 24 hours under oxidizing atmosphere by feeding oxygen gas with the pressure of 1 kg/cm2, gas flow rate 5 l/min and cooled in the furnace. The microstructures, Vickers microhardness and phase compositions were investigated. The results showed that the microstructures of the based metal revealed dendritic structure and they were transformed to equiaxed grains after internal oxidation. The internally oxidized layer of Ag-5Sn alloy is SnO2 with the hardness about 106-133 HV. The internally oxidized layer of Ag-5Cu alloy is CuO with the hardness about 65-73 HV.

scholarly journals Growth of 1-D TiO2Nanowires on Ti and Ti Alloys by Oxidation

2010 ◽  
Vol 2010 ◽  
pp. 1-7 ◽  
Author(s):  
Huyong Lee ◽  
Suliman Dregia ◽  
Sheikh Akbar ◽  
Mansour Alhoshan
Keyword(s):  
Flow Rate ◽  
Gas Flow ◽  
Oxidation Process ◽  
Treatment Temperature ◽  
Metal Oxidation ◽  
Gas Flow Rate ◽  
Simple Metal ◽  
Ti Alloys ◽  
Commercially Pure ◽  
Oxide Crystal

The growth of titania nanowires by a simple metal oxidation process was investigated for both commercially pure α-Ti and Ti alloys including Ti64 and β-Ti under a limited supply of oxygen. The effects of processing variables including heat treatment temperature, gas flow rate, and process duration on the growth of nanowires were explored. Similarities and differences in the growth of nanowires on pure Ti versus Ti alloys were observed. While the growth window in terms of temperature and flow rate is narrow in pure Ti, the window is much wider in the alloys. However, the trend towards high temperature is similar in all the samples promoting faceted oxide crystal growth rather than nanowires.

SCIENTIFIC AND ENGINEERING PRINCIPLES OF EFFICIENT FUEL USE AND ENVIRONMENTALLY FRIENDLY GAS COMBUSTION IN STOVE PLATES. PART 1. MODERN STATE-OF-THE-ART AND DIRECTIONS FOR IMPROVEMENT THE GAS BURNING IN DOMESTIC GAS COOKERS

2017 ◽  
pp. 3-18 ◽  
Author(s):  
B.S. Soroka ◽  
V.V. Horupa
Keyword(s):  
Natural Gas ◽  
Flow Rate ◽  
Gas Flow ◽  
Renewable Energy Sources ◽  
Combustion Process ◽  
Orifice Diameter ◽  
Firing Process ◽  
Gas Flow Rate ◽  
Gas Combustion ◽  
Gas Stoves

Natural gas NG consumption in industry and energy of Ukraine, in recent years falls down as a result of the crisis in the country’s economy, to a certain extent due to the introduction of renewable energy sources along with alternative technologies, while in the utility sector the consumption of fuel gas flow rate enhancing because of an increase the number of consumers. The natural gas is mostly using by domestic purpose for heating of premises and for cooking. These items of the gas utilization in Ukraine are already exceeding the NG consumption in industry. Cooking is proceeding directly in the living quarters, those usually do not meet the requirements of the Ukrainian norms DBN for the ventilation procedures. NG use in household gas stoves is of great importance from the standpoint of controlling the emissions of harmful components of combustion products along with maintenance the satisfactory energy efficiency characteristics of NG using. The main environment pollutants when burning the natural gas in gas stoves are including the nitrogen oxides NOx (to a greater extent — highly toxic NO2 component), carbon oxide CO, formaldehyde CH2O as well as hydrocarbons (unburned UHC and polyaromatic PAH). An overview of environmental documents to control CO and NOx emissions in comparison with the proper norms by USA, EU, Russian Federation, Australia and China, has been completed. The modern designs of the burners for gas stoves are considered along with defining the main characteristics: heat power, the natural gas flow rate, diameter of gas orifice, diameter and spacing the firing openings and other parameters. The modern physical and chemical principles of gas combustion by means of atmospheric ejection burners of gas cookers have been analyzed from the standpoints of combustion process stabilization and of ensuring the stability of flares. Among the factors of the firing process destabilization within the framework of analysis above mentioned, the following forms of unstable combustion/flame unstabilities have been considered: flashback, blow out or flame lifting, and the appearance of flame yellow tips. Bibl. 37, Fig. 11, Tab. 7.

On the Influence of Fluctuating Flow Rate Upon the Performance and Behaviour of Isothermal Reacting Systems

1998 ◽  
Vol 63 (6) ◽  
pp. 881-898
Author(s):  
Otakar Trnka ◽  
Miloslav Hartman
Keyword(s):  
Flow Rate ◽  
Gas Flow ◽  
Fluidized Bed Reactor ◽  
Computational Techniques ◽  
Continuous Stirred Tank Reactor ◽  
Gas Flow Rate ◽  
Solid Reaction ◽  
Continuous Stirred Tank ◽  
And Performance ◽  
Reacting Systems

Three simple computational techniques are proposed and employed to demonstrate the effect of fluctuating flow rate of feed on the behaviour and performance of an isothermal, continuous stirred tank reactor (CSTR). A fluidized bed reactor (FBR), in which a non-catalytic gas-solid reaction occurs, is also considered. The influence of amplitude and frequency of gas flow rate fluctuations on reactant concentrations at the exit of the CSTR is shown in four different situations.

scholarly journals Investigation on influences of loose gas on gas-solid flows in a circulating fluidized bed (CFB) reactor using full-loop numerical simulation

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Pengju Huo ◽  
Xiaohong Li ◽  
Yang Liu ◽  
Haiying Qi
Keyword(s):  
Numerical Simulation ◽  
Flow Rate ◽  
Gas Flow ◽  
Circulating Fluidized Bed ◽  
Separation Efficiency ◽  
Circulation Rate ◽  
Solid Mass ◽  
Gas Flow Rate ◽  
Gas Leakage ◽  
Mass Circulation

AbstractThe influences of loose gas on gas-solid flows in a large-scale circulating fluidized bed (CFB) gasification reactor were investigated using full-loop numerical simulation. The two-fluid model was coupled with the QC-energy minimization in multi-scale theory (EMMS) gas-solid drag model to simulate the fluidization in the CFB reactor. Effects of the loose gas flow rate, Q, on the solid mass circulation rate and the cyclone separation efficiency were analyzed. The study found different effects depending on Q: First, the particles in the loop seal and the standpipe tended to become more densely packed with decreasing loose gas flow rate, leading to the reduction in the overall circulation rate. The minimum Q that can affect the solid mass circulation rate is about 2.5% of the fluidized gas flow rate. Second, the sealing gas capability of the particles is enhanced as the loose gas flow rate decreases, which reduces the gas leakage into the cyclones and improves their separation efficiency. The best loose gas flow rates are equal to 2.5% of the fluidized gas flow rate at the various supply positions. In addition, the cyclone separation efficiency is correlated with the gas leakage to predict the separation efficiency during industrial operation.

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