dissolved gas
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Dissolved gas analysis (DGA) is recognized as one of the most reliable methods in transformer fault diagnosis technology. In this paper, three characteristic gases of transformer oil (CO, C2H4, and CH4) were used in conjunction with a Cr-decorated InN monolayer according to first principle calculations. The adsorption performance of Cr–InN for these three gases were studied from several perspectives such as adsorption structures, adsorption energy, electron density, density of state, and band gap structure. The results revealed that the Cr–InN monolayer had good adsorption performance with CO and C2H4, while the band gap of the monolayer slightly changed after the adsorption of CO and C2H4. Additionally, the adsorption property of the Cr–InN monolayer on CH4 was acceptable and a significant response was simultaneously generated. This paper provides the first insights regarding the possibility of Cr-doped InN monolayers for the detection of gases dissolved in oil.

An electricity board acquires several transformers from a manufacturer in a belief that their advertised lifetime of the transformer thus purchased is true. However, they don’t take in the case of negligence in maintenance of transformer, which is a strenuous job. The advertised thirty-year lifetime is reduced to a mere two-year lifetime, mainly because of the degradation of the insulation medium (Transformer oil), thus increasing losses in the transformer and decreasing its efficiency. The degradation of transformer oil leads to safety hazards like transformer bursting, consequently forcing the electricity board to replace the transformer, thus incurring huge amount of costs. This is the most relatable problem faced by the electricity board in every state. This research work aims at listing out various properties of transformer oil and ascertaining major impurities in a transformer oil by testing it using various techniques. The proposed work deals with long term observation and analysis of transformer oil to determine its degradation rate. Breakdown voltage, Moisture content, Resistivity, Acidity, Furan Analysis and Dissolved Gas Analysis were done using Mushroom electrodes, Karl Fischer Titration test, Tan delta test, Potassium Hydroxide Titration, High performance liquid chromatography, and dissolved gas analyzer respectively. The results reveal that, deviation of Breakdown Voltage, Moisture content, and 2-Furaldehyde (1197ppb) from the permissible limits can indicate the aging of the transformer.

Quantitative predictions of total dissolved gas (TDG) super-saturation are essential for developing operation schemes for high dams. Most TDG generation prediction models have various shortcomings that affect the accuracy of TDG super-saturation estimation, such as oversimplification of influencing factors and uncertainty in parameter values. In this study, the TDG generation process was divided into three parts, gas-liquid mass transfer process in the stilling phase, dilution resulting from the water jet plunging into the stilling phase, and outflow of TDG–super-saturated water from the stilling phase, while considering the water body and bubbles in the stilling phase as a whole. The residence time of the water in the stilling phase (Tr) was introduced to estimate mass transfer time, along with dimensional analysis methods. The properties of TDG generation were evaluated experimentally under varying Tr values. Based on the theoretical analysis and experimental results, a basic water renewal model was proposed and was validated using experimental data. Furthermore, prediction results of this model were compared with those of a classical empirical model and mechanical model based on observed data from a field survey at Xiluodu Dam. The results show that the relative errors between the predicted and experimental measurements were all less than 5%, indicating that the developed prediction model has a good performance. Compared with the mechanism model, the developed model could reduce the standard error (SE), normalized mean error (NME), and error of maximum (REMAX) by 60, 96, and 15%, respectively. Meanwhile, the developed model could reduce the SE, NME, REMAX by 17.4, 36, and 23%, respectively, compared with the empirical model. Considering all the error indexes, it can be concluded that the prediction performance of the water renewal model is the best among the three models. The proposed model was also more generically versatile than the existing models. Prediction results of water regeneration model for TDG could aid the drafting of governing strategies to minimize the risk of super-saturated TDG.

In power plant industries, boiler feed water (BFW) quality becomes the main parameter for steam generation, which is used for electricity production. To generate standard BFW for power plants, each impurity within water resources should be removed to prevent corrosion and scale deposition by several processes such as sedimentation, coagulation, polishing, and deaeration. Operation conditions that involved high temperature would trigger corrosion as a crucial factor in the maintenance and practical lifetime of the equipment. In the beginning of the operation, PT. Cirebon Electric Power (CEP) used All Volatile Treatment–Reduction (AVT-R) by injection of both ammonia and hydrazine. In order to optimize the operation, the BFW treatment was changed to All Volatile Treatment–Oxidation (AVT-O) that only uses of ammonia and deaerator for removing the dissolved gas. Based on the actual evaluation, AVT technology showed less performance related to corrosion prevention and high chemical consumption. Therefore, PT. CEP tried to implement modification in the BFW treatment, which is AVT technology to Oxygenated Treatment (OT). This paper is to evaluate the effect of those modifications on corrosion prevention and resource-energy saving. The modification into OT showed valuable results that decrease concentration of dissolved Fe from 1 ppb to 0.1 ppb in the deaerator outlet stream. This data reveals that good corrosion prevention can be achieved through the creation of passive layers, hematite Fe2O3. Oxygen injection into the water circulation system yielded an oxidation atmosphere so that the passive layer, Fe2O3, was formed. In addition to corrosion prevention, this modification also cut the amount of ammonia injection into the system from 2 ppm to 0.12 ppm. Reduction of that ammonia injection provides other benefits such as decreasing the volume of resin regeneration, which becomes only twice a month. This situation also created other benefits such as reducing the regeneration water, chemicals, and wastewater. Thus, the modification could establish the electricity production by PT. CEP more environmentally friendly and sustainable.A B S T R A KPada operasi PLTU, kualitas boiler feed water (BFW) menjadi parameter yang krusial untuk menghasilkan steam yang akan digunakan untuk memproduksi listrik. Untuk mendapatkan BFW sesuai dengan standar yang ada, maka pengotor di dalam air baku industri harus dihilangkan karena dapat menyebabkan korosi dan pembentukan kerak, baik pada pipa maupun peralatan. Kondisi operasi yang melibatkan steam pada suhu tinggi menyebabkan korosi menjadi masalah yang krusial terutama terkait dengan maintenance dan umur efektif pabrik. Pada awal berdirinya, PT. Cirebon Electric Power (CEP) menggunakan teknologi All Volatile Treatment–Reduction (AVT-R) dengan injeksi amonia dan hidrazin. Selanjutnya, dilakukan optimasi melalui perubahan proses menjadi All Volatile Treatment–Oxidation (AVT-O) dengan hanya menginjeksikan amonia dan mengoptimalkan fungsi deaerator untuk menghilangkan pengotor dissolved gas. Berdasarkan data lapangan, teknologi AVT yang digunakan kurang memberikan pencegahan korosi yang baik dan juga jumlah bahan kimia yang digunakan masih relatif banyak. Agar lebih ramah lingkungan dan handal, PT. CEP berusaha untuk melakukan modifikasi terhadap pengolahan boiler feed water (BFW) dari yang semula menggunakan teknologi AVT-O menjadi Oxygenated Treatment (OT). Penelitian ini bertujuan untuk mengevaluasi dampak modifikasi sistem AVT menjadi OT pada pencegahan korosi dan juga penghematan sumber daya. Modifikasi sistem AVT-O menjadi OT berhasil menurunkan konsentrasi dissolved Fe dari 1 ppb menjadi 0,1 ppb pada BFW. Hal ini menunjukkan terjadinya peningkatan pencegahan korosi melalui pembentukan double protective layer yang merupakan kombinasi magnetite (Fe3O4) dan hematite (Fe2O3). Injeksi oksigen ke dalam sistem mengubah kondisi air menjadi suasana oksidasi sehingga mampu mengubah dan membentuk lapisan baru sebagai pencegahan korosi. Selain pencegahan korosi, modifikasi ini juga berhasil menurunkan jumlah injeksi amonia dari 2 ppm menjadi 0,12 ppm dalam siklus air yang ada. Penurunan jumlah injeksi amonia ini akan memberikan keuntungan beruntun berupa berkurangnya frekuensi regenerasi resin dari semula 8 menjadi 2 kali perbulan. Kondisi ini akan menghasilkan penghematan sumber daya berupa kebutuhan air untuk regenerasi, bahan kimia amonia, dan beban pencemaran. Oleh karena itu, modifikasi ini telah membuat proses produksi listrik di PT. CEP lebih ramah lingkungan dan berkelanjutan.Kata kunci: All Volatile Treatment (AVT); efisiensi energi; korosi boiler; Oxygenated Treatment (OT)

Existing gas production technologies limit gas recovery at the level of 85 %. Therefore, it is important to introduce technologies that make it possible to maximize the volume of production and intensify the inflow; for their selection it is important to have a reliable estimate of the residual gas reserves, since with a significant volume of the aquifer of gas fields, the volume of dissolved gas can be up to 10 % of the total reserves of the reservoir, which should be taken into account when designing the application of technologies to increase gas recovery.The main hydrocarbon dissolving in reservoir water is methane. In this regard, it is of interest to study methods that make it possible to determine the volume of hydrocarbon gases dissolved in saline water, which will make it possible to determine the total reserves of such gas. We investigated the existing methods for calculating the amount of methane dissolved in reservoir water, and gave a quantitative assessment of the volume of gas dissolved in water.

The type and concentration of dissolved gases in transformer insulating oil are used to assess transformer conditions. In this paper, an online detection setup for measuring the concentration of multicomponent gases dissolved in transformer insulating oil is developed, which consists of an oil-gas separation system and an optical system for acquiring the transformer status in real time. The oil-gas separation system uses low pressure, constant temperature, and low-frequency stirring as working conditions for degassing large-volume oil samples based on modified headspace degassing. The optical system uses tunable diode laser absorption spectroscopy (TDLAS) to determine the gas concentration. Six target gases (methane, ethylene, ethane, acetylene, carbon monoxide, and carbon dioxide) were detected by three near-infrared lasers (1569, 1684, and 1532 nm). The stability of the optical system was improved by the common optical path formed by time-division multiplexing (TDM) technology. The calibration experiments show that the second harmonics and the concentrations of the six gases are linear. A comparison experiment with gas chromatography (GC) demonstrates that the error of acetylene reaches the nL/L level, while the other gases reach the μL/L level. The data conforms to the power industry testing standards, and the state of the transformer is analyzed by the detected six characteristic gases. The setup provides an effective basis for the online detection of dissolved gas in transformer insulating oil.

Abstract CWI is affected by multiple factors, including the wettability of the rock. These experiments seek to determine the results that are obtained when CW is injected in a tertiary mode for systems: (1) wetted by water and (2) mixed wettability; to date, no study has used this approach. The same sandstone core was used in all trials, and each test consisted of saturating the core with live crude, followed by the injection of water as a secondary recovery and then the injection of CW as a tertiary recovery. An additional sensitivity test was conducted that consisted of varying the composition of the dissolved gas in the crude. In general, in a water wet system, the recovery associated with the injection of CW is higher (normalized) compared to a mixed wettability system. This does not mean that the results were negative in the mixed system. On the contrary, the results are positive since on the order of an additional 20% was recovered. However, the pressure differential in a mixed system is higher (14%) compared to water wet system. Although it is common knowledge that wettability of the rock affects the production and pressure results in an experiment, these are the first experiments that have been performed exclusively to determine quantitatively the response to CWI while maintaining the other parameters constant.

The method of fault diagnosis based on dissolved gas analysis (DGA) is of great importance to detect possible failures in the transformer and to improve the safety of the electrical system. The DGA data of the transformer in the smart grid has the characteristics of a large amount, different types and a low density of values. Since the power transformer is an important type of power supply in the electrical network, this document provides a complete overview of the power transformer and describes how to diagnose faults. Furthermore, on-line monitoring, the method of fault diagnosis and condition-based maintenance strategy decision-making method as also have been described. The paper presents detailed literature on the recent advancements and methods being adopted by various authors on fault detection.