Results 1 - 10 of 1471
Results 1 - 10 of 1471. Search took: 0.024 seconds
|Sort by: date | relevance|
[en] This paper deals with the effects of oxygen treatment on scale growth in a boiler tube. For experimental study, specimens were picked from the boiler tube(13CrMo44) of domestic fossil power plants and then for scale growing, the specimens were immersed in 350 .deg. C boiler feedwater at various dissolved oxygen contents(before heating) and immersion times. Characteristics of the scale were investigated by analysing the components of the scale and comparing the ratio of components using SEM and XRD. The scale formed in 0 ppm(before heating) dissolved oxygen boiler feedwater was found to be magnetite. where magnetite and hematite were formed simultaneously in the case of 8 ppm or more dissolved oxygen boiler feedwater. Further, the amount of magnetite was more than that of hematite. It is also suggested that the dissolved oxygen help form hematite and the hematite reduces the growth of scale
[en] Oxidation tests of austenitic steel Super304H and HR3C were conducted at 550-600 °C in supercritical water under 25 MPa with the dissolved oxygen content. The oxidation rate of Super304H rapidly increased with increasing temperature, while the weight change of HR3C at 600 °C is slightly larger than that at 550 °C. A double-layer oxide scale developed on Super304H and HR3C steel, which was made up of an Fe-rich outer layer and a Cr-rich inner layer. The criterion contents of Cr were calculated for Super304H and HR3C. The effect of temperature and the Cr content on oxidation rate and oxide composition were discussed.
[en] Oxygen scavengers are usually added to boiler water to stop the steel body of the boiler being oxidized. The choice of an oxygen scavenger must take into account its effectiveness, availability, toxicity and cost. Hydrazine and hydroxylamine are commonly used to inhibit boiler corrosion. Diethylhydroxylamine, (Dehpa) has been reported as a useful alternative compound, it is less toxic than hydrazine and hydroxylamine. Consequently the use of this compound as a corrosion inhibitor is likely to increase in parallel with the present-day rising of safety at work standards. Therefore it was decided to develop a method for the determination of diethylhydroxylamine in water samples. The method reported is highly selective, sensitive, and rapid and gives a good reproducibility for the determination of ultra-trace amounts of diethylhydroxylamine residues in boiler water after use of the diethylhydroxylamine as an oxygen scavenger. It allows the diethylhydroxylamine concentration in water samples to be determined over the ranges 36-460ppb and 178-2140ppb, with a relative standard deviation of less than 1% . the method is based on the inhibition of the bleaching of Reumazol Brilliant Blue by oxidation with chloramine-T.
[en] Designed to reduce oxygen concentrations in water storage and makeup systems from fully aerated conditions of 8000ppb to 10ppb in a single pass, the Westinghouse catalytic oxygen removal system (CORS) is a proven alternative to other methods of deoxygenation. (author)
[en] The physical properties of polypropylene (PP) hollow fiber membranes and its deoxygenation efficiency were investigated. We supposed the conditions of PP hollow fiber membranes under radiation field and irradiated the PP membranes using differential scanning calorimetry(DSC), thermal gravimetric analyzer (TGA), fourier transform infrared (FT-IR), and contact angle. In addition, the deoxygenation efficiency of the exposed PP membranes was estimated by using an oxygen removal test kit. From the results, we found that the physical properties and deoxygenation efficiency of PP membrane was still keep good condition under the simulated radiation field
[en] The dissolved oxygen in the reactor coolant causes the corrosion of material and deterioration of the capacity of radiation shield. Recently, catalyst resin or degassing membrane is used instead of chemical agents to remove the dissolved oxygen in the reactor water. The Hybrid system intended to remove the dissolved oxygen creates an ideal combination between hollow fiber membrane module which is small but effective in removing dissolved oxygen and the module created by using Pt catalyst reaction of platinum on the surface of ACF(Activated Carbon Fiber) which has fairly large surface area for its weight and easy to impregnate. This system maximizes efficiency and the treatment volumn. This system is highly efficient degassing equipment that has more than 99.9% of DO removal efficiency in a once-through process
[en] This study aimed at assessing the impact of some wells abiotic factors on the antimicrobial susceptibility of Pseudomonas aeruginosa isolated. A total of 14 well waters of Douala and Yaoundé towns (Cameroon, Central Africa) were chosen. Fifteen antibiotics were used to test antimicrobial susceptibility with the majority belonging to β-lactam, aminoglycoside and quinolone groups. Result showed that in Douala, electrical conductivity of water ranged from 145.38 to 559.69 μS/cm in well, while in Yaoundé, it ranged from 172.5 to 710.2 μS/cm. Dissolved oxygen ranged from 2.5 to 5.5 mg/l and from 3.9 to 5.1 mg/l, respectively, in Douala and Yaoundé. Organic matter varied from 2.3 to 7.2 mg/l and 1.4 to 5.2 mg/l in Douala and Yaoundé, respectively. As for pH, it fluctuated between 5.56 and 6.66 CU and between 5.1 and 7.0, respectively, in Douala and Yaoundé. The sampled waters harbour multi-drug-resistant P. aeruginosa strains. About 20.40% of strains from wells in Yaoundé metropolis expressed resistance to at least 5 antibiotics, whereas from wells in Douala town, up to 33.33% of strains were resistant to at least 8 antibiotics including ticarcillin, ceftazidime and gentamicin. The effect of abiotic factors on the sensitivity to antibiotics was assessed using the multiple regression tests. In both towns, less than 5% in the changes of physicochemical parameters of well waters explained the variance in inhibition diameter values of antibiotics (p ≤ 0.05). The pH significantly impacts on antimicrobial susceptibility. Environmental conditions are less stressful for P. aeruginosa and fairly affect its antimicrobial susceptibility.
[en] Dissolved gas analysis is the most important tool in determining the condition of a transformer. It is the first indicator of a problem and it can identify deterioration of insulation and oil, hot spots, partial discharges and arcing. Transformers are very complex and expensive equipment and it is important to diagnose the fault quickly and accurately. Keeping records, comparison to the previous analysis and consultation with experienced staff is necessary to make a correct decision for the condition of the transformer and following measures that should be taken in order to avoid bigger and more expensive repairs. This brief introduction to the dissolved gas analysis will be of great use to the engineers involved in maintenance of power transformers. The paper is presented within my post-graduated studies in the Power System Department at the Faculty for Electrical Engineering. (Author)
[en] It was recently discovered that significant erosion/corrosion occurs with machinable tungsten when exposed to water, particularly when the water has dissolved oxygen present. The problem was first discovered about 1 1/2 years ago when extensive corrosion was found inside the cooling channels of the L5-80 white-beam slits located in sector 3-ID-A. Figure 1 and Figure 2 show cut-away sections of the tungsten slit; the water passages are severely corroded from the cooling water used to cool the slit. The problem was brought to the attention of the world's two largest manufacturers of machinable tungsten, Mi-Tech Metals from Indianapolis, IN and Kulite Tungsten Corp. from East Rutherford, NJ. Neither company had any experience with this problem and were unaware that water could cause such significant corrosion, apparently the APS was the first customer to ever use the material in this fashion