Papers by Keyword: Co

Abstract: It is well known that CO and microparticles generated during GMAW welding processes can affect the welder's health and the environment quality and should be avoided. The main goal of the research was to quantitatively assess the concentrations of CO and microparticules resulting through melted wire - shielding gas - welding pool interaction, specific to fusion welding process, in particular MAG-M (Metal Active Gas with Corgon shielding gas)) process. The concentrations of microparticles and emission of CO developed by several combinations of filler metal and shielding gas, such as ordinary solid wire, basic flux-cored wire, rutile flux-cored wire, metal powder cored wire, low fume metal powder cored wire and Corgon 18, as shielding gas mixture, have been monitored and investigated in detail. The experimental data, achieved for different wire feed speed values, were collected by using special devices as Multilyzer NG and MicroDust Pro and further processed, plotted and comparatively analysed. The analysis revealed that the low fume rutile flux-cored wire significantly developed lower concentrations of microparticles and CO, in comparison with the other types of wires used in MAG-M welding process, and a better protection of the environment would be achieved. Important conclusions related to the influence of the wire type on the concentrations of CO and microparticles produced during MAG-M welding process have been drawn and some recommendations useful for the producers of welded structures are provided at the end of the paper.

Abstract: The effects of Co from 0 to 11.60 % (in mass fraction) on the solidification and precipitation behaviors of IN 718 alloy had been investigated. The results showed that the volume fraction of the dendrite core increased with the addition of Co. In the alloys with 0-5.84 %Co, the addition of Co could restrain the precipitation of blocky Laves phase and promoted the formation of eutectic Laves phase. In the alloys with 9.00-11.60 % Co, the eutectic gray phase and small blocky Laves phase precipitated in the interdendritic region. The eutectic gray phase increased and small blocky Laves phase decreased with increasing Co. The parallel lath-like δ-Ni₃Nb phase was observed to precipitate in some interdendritic region without the formation of gray phase and Laves phase in the 9.00-11.60 % Co alloys. Further research found that Co slightly segregated in the dendrite core and markedly raised the solubility of element Mo in the dendrite core which resulted in reduced Mo in the residual liquid, and consequently, restrained Laves phase while promoted the precipitation of Mo-depleted gray phase and δ-Ni₃Nb phase. Furthermore, Co was seemed to elevate the solidification point of the γ matrix while decrease that of the Laves phase.

Abstract: Reburning technology has been developed to adopt various commercial combustion systems. Fuel lean reburning is an advanced reburning method to reduce NOx economically without using burnout air, however it is not easy to get high NOx reduction efficiency. In the fuel lean reburning system, the localized fuel rich eddies are used to establish partial fuel rich regions so that the NOx can react with hydrocarbon radical restrictively. In this paper, a new advanced reburning method which supplies reburn fuel with oscillatory motion is introduced to increase NOx reduction rate effectively. To clarify whether forced oscillating injection of reburn fuel can effectively reduce NOx emission, experimental tests were conducted in vertical combustion furnace. Experiments were performed in flames stabilized by a gas burner. The natural gas is used as both main and reburn fuel and total thermal input is about 40kW. The forced oscillating injection of reburn fuel is realized by electronic solenoid valve, so that fuel rich region and fuel lean region is established alternately. In the fuel rich region, NOx is converted to N₂ by reburning reaction, however unburned hydrocarbon and CO is oxidized in fuel lean zone and mixing zone at downstream where slightly fuel lean region is formed by mixing of two regions. The NOx reduction rate increases up to 41% by forced oscillating reburn motion. And this paper makes clear that in order to decrease NOx when oscillating reburn fuel injection system is adopted, the control of factors such as frequency and duty ratio is very important.

Abstract: Montmorillonite pillared by mixing Fe, Fe-Cr, Al-Fe and Cu-Al complexes was investigated for their catalytic activities for Water Gas Shift Reaction (WGSR). Element chemical analysis showed that the content of Fe, Fe-Cr, Al-Fe catalysts were 26.93%, 31.03%, 28.20%, respectively. Compared with the traditional shift catalyst, in the same shift condition, we can use the PILC catalysts to substitute. Using PILC catalysts can accurately control the constitution of synthesis gas over changing shift rate.

Abstract: The electronic properties of Mn-doped Fe₂O₃ and the adsorption of CO on Mn-doped Fe₂O₃ were investigated using density functional theory (DFT) calculations. Mn doping Fe₂O₃ is endothermic process, and high-folded doping is easier than lower-folded doping. Mn-doping changes the conduction and valence band of Fe₂O₃ (104) more obviously than Co-doping. Energy separation between CO molecule and oxygen carrier suggests that electron transfering between CO and high-folded doping surface is easier than between CO and any other low-folded doping surfaces. Then, CO adsorptions on different sites of Mn-doped Fe₂O₃ were further investigated, which shows that Mn decreases the interaction between CO and the surface except for Mn_7f-doped Fe₂O₃ (104). Results promote the fundamental understanding of such metal-doped oxide surface for further application.

Abstract: Reaction activities of Ni-doped and Cu-doped Fe₂O₃ oxygen carriers (OCs) with CO were investigated using thermo gravimetric (TG-DTG).The structures of the prepared OC were characterized by X-ray diffract meter (XRD).TG-DTG investigations indicated that rational Ni and Cu doping could efficiently enhance the reactivity of Fe-base oxygen carrier for oxidizing CO under different conditions. And Fe-based OC doped with 20 wt. % Ni can realize the highest reactivity.

Abstract: : The population explosion in India is causing heavy consumption of energy resources. Most of the transportation sector is based on diesel as fuel. In this regard, it is high time for the search of renewable alternative fuels to reduce the dependency of oil imports. The usage of fossil fuels is also causing environment pollution. To minimize the pollution, an alternative to diesel is found to be non edible Mahua oil. In the present work, experiments were carried out on Mahua oil methyl ester (MOME) fuel and evaluated its performance at different injection pressures ranging from 190 to 220bar with the increment of 10 bar. The effect of blending of MOME with diesel at different injection pressures were studied experimentally to evaluate the brake thermal efficiency, brake specific energy consumption (BSEC), carbon monoxide (CO), and unburnt hydrocarbon (HC) emissions. It was observed from experimental results that 20% MOME (B20) have higher thermal efficiency at 190 bar compared with pure diesel and also HC and CO emissions were reduced.

Abstract: This paper focuses on the monitoring of indoor air quality parameters, namely: indoor temperature, humidity, velocity, particulate matter, carbon monoxide and carbon dioxide in day care centres. This study selected 15 day care centres located in Kuala Lumpur, Malaysia. These day care centres were categorized as follows: (1) day care centers near an industrial area, (2) day care centers near a main road, and (3) day care centers in a residential area. The obtained data showed that the values for the indoor air quality parameters in all day care centres were still well below the recommended value according to the Department of Safety and Health, Malaysia. The day care centers near an industrial area had the highest value of carbon monoxide, and carbon dioxide as compared to the day care centers near a main road and the day care centers in a residential area. The average concentrations of carbon monoxide, and carbon dioxide in the day care centers near an industrial area were 3.67 ppm and 801.56 ppm respectively. Meanwhile, the carbon monoxide, and carbon dioxide in the day care centers near a main road area and the day care centers in a residential area were 3.13 ppm, 768.22 ppm, 2.92 ppm and 733.70 ppm, respectively.

Abstract: Abstract. It is shown, by the combination of SNMS, (Secondary Neutral Mass Spectrometry), XRD, XPS and APT (Atom Probe Technique) that the growth of the Cu₃Si crystalline layer at 408 K between the amorphous Si and nanocrystalline Cu thin films follows a linear law and the shifts of the Cu₃Si/Cu and Cu₃Si/a-Si interfaces approximately equally contributed to the growth of this phase. It is also illustrated that the Si atoms diffuse fast into the grain boundaries of the nanocrystalline Cu, leading to Si segregation. Both the SNMS and APT results indicate that even during the deposition of Cu on the amorphous Si an intermixed region is formed at the interface. This region easily transforms into a homogeneous Cu₃Si crystalline reaction layer subsequently which further grows following apparently an interface controlled linear kinetics. Similar experiments performed in Co/a-Si system to study the formation and growth kinetics of the intermetallic phase. However, interestingly, homogenous formation of the new phase at the Co/a-Si interface was not always observed.

Abstract: Co-doped Fe₂O₃ oxygen carriers reacted with CO were investigated in order to study the temperature effect on the redox characterization.Co-Fe₂O₃ were characterized with X-ray diffraction (XRD), BET and transmission electron microscope (TEM), which showed that the surface structure was regular, and the polymorph was stable. The TG (Thermo Gravimetric Analyzer) analysis indicted that, rational doping Co could enhance the reactivity of iron-base oxygen carrier reacted with CO under different conditions. Oxygen carrier with Fe: Co molar ratio of 1:0.1 had best reactivity. With the temperature increased, the reduction degree became deeper and the complete conversion time shortened. The reduction reaction Co_0.1Fe oxygen carrier with CO was carried out step by step, and the entire process was divided into three stages, namely 344.7-391.0, 414.7-472.5 and 607.6-681.5°C.