Oil health index calculation and incipient fault diagnosis in power transformers using fuzzy logic

In this paper, a new fuzzy logic (FL) model is proposed for assessing the health status of power transformers. In addition, the detection of incipient faults is achieved where two or more faults exist simultaneously. The process is carried out by integrating a fuzzy logic model with the conventional International Electric Committee (IEC) ratio codes method. As transformer oil insulation deteriorates, excess percentages of dissolved gases such as hydrogen, methane, ethane, acetylene and ethylene are induced within the trasnformer. The status of oil health is generally assessed using these gas concentrations. Therefore, in the proposed model, 31 fuzzy rules are designed based on the severity levels of these gases in order to determine the health index (HI) of the oil. Similarly, any incipient faults along with their severity are also detected using the proposed fuzzy logic model with 22 expert rules. To validate the proposed fuzzy logic model, the data for dissolved gases in 50 working transformers operated by the Himachal Pradesh State Electricity Board (HPSEB), India, are collected. Over the years, calculations for the health index have been performed using conventional dissolved gas analysis (DGA) interpretation methods. The shortcomings of these methods, such as non-reliability and inaccuracy, are successfully overcome using the proposed model. The detection of incipient faults is normally performed using key gas, Rogers ratios, the Duval triangle, Dornenburg ratios, modified Rogers ratios and the IEC ratio codes methods. The shortcomings of these conventional ratio code methods in identifying incipient faults in some typical cases, ie multiple incipient fault cases, are overcome by the proposed fuzzy logic model.

Hydrochemical and Hydroacoustic Investigation of the Yugama Acid Crater Lake, Kusatsu-Shirane, Japan

The gases dissolved in the waters of volcanic lakes can present a serious hazard if the physical-chemical conditions change due to variations in the supply of magmatic gases. The monitoring of gases such as CO2 and He help us understand the degassing process and their connection with magmatic/hydrothermal system. One of the most acidic volcanic lakes on the planet is the Yugama, on Kusatsu Shirane volcano (Japan). We report the results of an interdisciplinary study carried out in August 2013 at Yugama consisting of the first estimation of rate of diffuse CO2 emission, the chemical and isotopic analysis of water and dissolved gases in samples from vertical lake profiles, and an echo-sounding survey. The lake water has an average temperature of 24-25°C, pH 1.01, concentrations of SO42- between 1,227 and 1,654 mgL−1 and Cl− between 1,506 and 2,562 mgL−1, with gas bubbling at several locations and floating sulfur globules with sulfide inclusions. A total of 66 CO2 efflux measurements were taken at the lake surface by means of the floating accumulation chamber method to estimate the diffuse CO2 output from the studied area. CO2 efflux values ranged from 82 up to 25,800 g m−2 d−1. Estimation of the diffuse CO2 emission at Yaguma Crater Lake was 30 ± 12 t d−1. Normalized CO2 emission rate (assuming an area of 0.066 km2) was 454 t km−2 d−1, a value within the range of acid volcanic lakes. Vertical profiles of major ions and dissolved gases showed variations with increases in ion content and dissolved CO2 and He with depth. Acoustic imaging shows the presence of intense bubbling and provides important information on the bathymetry of the lake. The 50–200 kHz echograms exhibit frequent vertical plumes of rising gas bubbles. Within the crater-lake, three circular submarine vents have been identified showing flares due to a significant activity of sublacustrine emissions. This work shows the first data of diffuse CO2 degassing, dissolved gases in water and echosounding (ES) from Yugama Crater Lake. Periodic hydrogeochemical and hydroacoustic surveys at Yugama Crater Lakemay thus help to document changes in the state of activity of this high-risk volcanic area.

Geochemistry of water-soluble gases in the oil and gas bearing sediments of the zone of junction between the Yenisei-Khatanga and the West Siberian basins (the Arctic regions of Siberia)

The results of the studies of geochemical and zoning features of water-dissolved gases in the Mesozoic sediments of the junction between the Yenisei-Khatanga and the West Siberian basins are reported. The stage of industrial oil and gas content is more than 3 km thick and involves the depth range from 750 to 4000 m. Waters occurring in the region contain methane, their total gas saturation is 0.3 to 4.6 dm3/dm3, and CH4 content in 88.9 to 95.4 vol. % on average. An increase in the concentrations of carbon dioxide and methane homologues is observed with an increase in the depth, which is accompanied by a regular decrease in the concentrations of methane and nitrogen. In general, water-dissolved gases from the Neocomian and Jurassic reservoirs have similar compositions (С1 > N2 > C2 > C3 > n-C4 > i-C4 > CO2 > i-C5 > n-C5). The water-dissolved gases of the Aptian-Albian-Cenomanian sediments are distinguished by lower concentrations of methane homologues (С1 > N2 > C2 > CO2 > C3 > i-C4 > n-C4 > i-C5 > n-C5), with the total content of heavy hydrocarbons (HHC) equal to 1.44 vol. %. Vertical zoning of the composition of water-dissolved gases is determined by the distribution of hydrocarbon pools in the Jurassic-Cretaceous section. A regular increase in the average values of the factor of enrichment with hydrocarbons (HC) (from 37 to 154) was established, along with a decrease in the ratio of CH4/ƩHHC (from 130 to 7), C2H6/C3H8 (from 41 to 2) and i-C4H10/n-C4H10 (from 2.6 to 0.6) from the Aptian-Albian-Cenomanian reservoirs to the Jurassic ones. The zone with anomalous He concentrations within the range of 0.4–0.9 vol. % was detected in the Neocomian and Middle Jurassic sediments. This zone is localized at the north-western slope of the Messoyakh inclined ridge (the Anomalnaya, Turkovskaya, Pelyatkinskaya and Sredne-Yarovskaya areas). The nature of this anomaly needs further studies.

Fluidics system for resolving concentration-dependent effects of dissolved gases on tissue metabolism

Oxygen (O2) and other dissolved gases such as the gasotransmitters H2S, CO and NO affect cell metabolism and function. To evaluate effects of dissolved gases on processes in tissue, we developed a fluidics system that controls dissolved gases while simultaneously measuring parameters of electron transport, metabolism and secretory function. We use pancreatic islets, retina and liver from rodents to highlight its ability to assess effects of O2 and H2S. Protocols aimed at emulating hypoxia-reperfusion conditions resolved a previously unrecognized transient spike in O2 consumption rate (OCR) following replenishment of O2, and tissue-specific recovery of OCR following hypoxia. The system revealed both inhibitory and stimulatory effects of H2S on insulin secretion rate from isolated islets. The unique ability of this new system to quantify metabolic state and cell function in response to precise changes in dissolved gases provides a powerful platform for cell physiologists to study a wide range of disease states.

Role of Purged Air On Synthesis of Mesoporous NiO/C Composite And Its Application On Waste Water Treatment

Two different methods were employed to synthesis NiO/C composite from agricultural waste. The mesoporous composite was successfully synthesized via a novel precipitation method in the presence of dissolved gases. The morphology of the composites were differentiated by characterisation techniques such asx-ray Diffraction (XRD), the point of zero charge (pHpzc), field emission scanning electron microscope (FESEM), Fourier transform infrared spectroscopy (FTIR), energy dispersive x-ray analysis (EDAX) and vibrating sample magnetometer (VSM). Then, the mechanism of synthesis was elucidated using the above experimental characterisation data. FESEM and EDAX report of Ni(OH)2-carbon composite clearly showed the role of dissolved gases on synthesis. Both the composites were subjected as the adsorbent to eliminate/remove the toxic Pb(II) ions from the wastewater. Batch adsorption experiments were carried out to compare the Pb(II) ions removal capability of both the composite materials. The parameters such as the effect of pH, the dosage of the adsorbents and initial concentration were studied. At the optimized conditions, isotherm studies for each of the adsorbents were also carried out. The isotherm results revealed that the maximum removal capacity qe (mg/g) was 30.78 for PJNC and 43.48 for PJGNC. The VSM analysis confirmed that both the adsorbents were soft magnetic materials. Hence, they could be competently separated from salted/treated water using the magnetic field.

Diffusive Transport of Dissolved Gases in Potential Concretes for Nuclear Waste Disposal

In many countries, the preferred option for the long-term management of high- and intermediate level radioactive waste and spent fuel is final disposal in a geological repository. In this geological repository, the generation of gas will be unavoidable. In order to make a correct balance between gas generation and dissipation by diffusion, knowledge of the diffusion coefficients of gases in the host rock and the engineered barriers is essential. Currently, diffusion coefficients for the Boom Clay, a potential Belgian host rock, are available, but the diffusion coefficients for gases in the engineered concrete barriers are still lacking. Therefore, diffusion experiments with dissolved gases were performed on two concrete-based barrier materials considered in the current Belgian disposal concept, by using the double through-diffusion technique for dissolved gases, which was developed in 2008 by SCK CEN. Diffusion measurements were performed with four gases including helium, neon, methane and ethane. Information on the microstructure of the materials (e.g., pore size distribution) was obtained by combining N2-adsorption, mercury intrusion porosimetry (MIP), scanning electron microscopy (SEM) and water sorptivity measurements. A comparison was made with data obtained from cement-based samples (intact and degraded), and the validity of existing predictive models was investigated.