Papers by Keyword: Power Plant

Abstract: Oxide dispersion strengthening steel (ODS) is widely used in high-severity environments in supercritical water gasification (SCWG) due to its high-temperature corrosion resistance and fatigue strength. Nano-oxide can be used as reinforcement for ODS steel to enhance the mechanical properties by retarding dislocation at grain boundaries. This work aims to study the fabrication of Fe-18Cr ODS steels reinforced with 0.5-3.0 wt% nano-Al₂O₃ contents. The microstructure of ODS steels before and after sintering processes was observed by an optical microscope, and the hardness test was conducted by a Micro-Vickers hardness tester. The results showed the mass gain increased by 49.18±10.75 mg cm^-2 due to the formation of Fe₂O₃ during the sintering process. The average porosity of ODS steels after sintering decreased by about 60% due to thermal contraction, resulting in their average densities increased by around 7 %. Moreover, the hardness of Fe-18Cr ODS steels increased up to 120 HV with the increase in nano-Al₂O₃ percentage.

Abstract: The paper provides a comparative assessment of using four types of fuel ashes from different types of coal combustion as additives to replace part of the cement in producing a composite binder. The authors assessed the effectiveness of the additives by cement dough properties (water-binder ratio, normal density, initial setting) and the strength of the binder at 1, 3, 7 and 28 days of hardening. The ashes are ranked according to their efficiency in the structure of composite binder in the following sequence: acid ash from Reftinskaya power plant → acid ash from Novotroitskaya power plant → basic ash from Nazarovskaya power plant → acid ash from Troitskaya power plant. The research revealed that the most effective mineral additives were basic ash from the Nazarovskaya power plant and acid ash from the Troitskaya power plant. Their use reduced the amount of cement by 15% and 25% respectively, while reducing the strength by no more than 3%.

Abstract: The aim of this study is to evaluate the potential impacts of 8.5 MW thermal power plant on soil and water quality within its location, Lekki area, Lagos State. The study area was geo-referenced using the existing map and Geographical Positioning System. Auger was used to sample soil at three different locations within the power plant. The soil samples were prepared and analyzed for the following parameters using standard analytical methods. The parameters include soil texture, Exchangeable cations and anions (H⁺, Na⁺, Ca²⁺, Mg²⁺, Cl^- and SO₄^2-) Nutrients compounds (NO₃-, Total Nitrogen (TN), Organic Carbon (OC) and heavy metals (Fe, Cd, As, and Mn). Surface and groundwater samples were collected within the power plant in triplicate and analyzed for true colour, turbidity, conductivity, salinity, THC and Coliform. Dissolved Oxygen (DO), BOD₅, Total Organic Carbon (TOC), Organic Matter (OM) and heavy metals (As, Ag, Fe and Mn) of water samples were also analyzed. The soil from the study area is loamy-sand in texture. The average As, Ag, Fe and Mn in surface and groundwater samples were 0.055, 0.025, 3.150, 0.735 and 0.12, 0.080, 6.440 and 0.180 mg/L, respectively. The gas-fired power plant has contaminated the soil and water within its premises with petroleum and heavy metals. The engine stack should be modified to minimize the pollution effects of the power plant on the environment.

Abstract: The increasing market share of highly volatile electricity generated from renewable sources like wind or solar energy, leads to enormous challenges in the energy sector. Since large-scale storage systems are neither currently nor in the near future available, the gap between electricity from renewable sources and current electricity demand has to be closed with flexibly operated conventional power plants. In order to be a viable, cost-effective option in tomorrow’s energy market future power plants must be highly efficient while having low CO₂ emissions. Furthermore, they have to be highly reactive to counter instabilities in the electrical grid due to fluctuations in renewable sources. Current materials used in power plants are only within limits suited to experience extreme changes in operational loads. However, extreme changes of operational loads will become increasingly severe with a growing share of renewables. Our project team has developed a new concept for CMC-jacketed pipes to alleviate these issues. Recently, this concept was further developed and tested in laboratory as well as a large-scale application test at Grosskraftwerk Mannheim (GKM). All tests are still ongoing. Additionally, to the use in modern highly efficient power plants such CMC-jacketed piping is also suitable for other high-temperature applications, like e.g. solar power plants or industrial chemical applications.

Abstract: This work presents an experimental case study of 200 MW low-pressure steam turbine rotor blades damage after 310 thousand hours of operation and 404 start-ups on the power plant. Damaged blade material was analysed by experimental testing of mechanical properties as well as crack initiation and microstructure in the damaged area by using optical and scanning electron microscopes, and investigation of chemical composition by the SEM-EDS method. Results of the investigation show that the material was die forged martensitic steel 20Cr13. The mechanical properties of the blade steel were in accordance with standard technical requirements for new material. The cross-sections of damaged and undamaged blades were investigated and compared. It was found that thickness of damaged blades was significantly less than undamaged ones. SEM-EDS analysis has shown the presence of brass fragment on the surface of one damaged blade. The microstructural analysis has shown that one of the cracks was initiated due to impact of brass fragment. Based on the given case study results it is concluded that the reason of the blade damage was a combination of at least two factors: accelerated high cycle fatigue due to increased stresses caused by excessive vibration of damaged blades with lower thickness and impact of brass fragment against blades.

Abstract: Main object of this paper are results of ash usage in order to create artificial aggregates. Ashes are mineral residue of coal burning in thermal power stations. Fly ashes (high temperature ashes) are highly used in practice as supplement of cement and silicate components of silica materials. FBC ashes are not used such great scale. They can be used for restoration, mounds or for example also for production of ash autoclaved aerated concrete. [1] Production of artificial aggregate from sintered ash is possible mainly because of the fly ashes. [2] Focus of this paper is to compare various types of ashes for lightweight aggregate produced with cold-bonding. Apart from the fly ashes and FBC ashes are also tested bottom ashes from FBC technology. From the results could be assumed, that bottom ashes compared to their granularity could be used only very hardly. Fly ashes splendidly react with cement and reach higher strengths. But they need more than 10 % of binder in order to reach quality results. FBC ashes better cooperate with quicklime, but in order to reach suitable parameters they need smaller portion of binder.

Abstract: This article presents the availability of 4 large scale grid connected photovoltaic (PV) power plants that located in Petchaboon, Nakhon Sawan, and Chai Nat province of Thailand. These power plant size are 4.5 MW and 6.5 MW. In addition, they are constructed with the same platform, component, and commercial operation date (COD) in the same year. The data were collected during 1^st August 2012 to 31^st October 2014. The study result found that availability of these power plant is over 97 % every year except Nakhon Sawan 1 plant in the first year. The internal unavailability trend is quickly reduce while external unavailability is randomly fluctuation.

Abstract: The use of fossil energy in Indonesia shown an increasing trend in all sectors every year^[1]. Petroleum is still ranked the highest, ie 51.66%. Natural gas occupying the second level, ie 28.57%. The rest of the energy is supplied by 15.34% oil and 4.43% renewable energy. Besides this, the dominance of fossil fuel use give a major impact on air quality^[2]. Emissions from fossil fuel burning add 6.3 GtC/year (compared to a stock of fossil fuels of 16,000 Gt C) while another 2.3 Gt C/year is reabsorbed into the ocean^[3]. Therefore, it is necessary to develop the use of renewable resources to generate environmentally friendly electricity. One of the energy resource that can developed is ocean current energy. In 2009 in the Strait of Nusa Penida has been conducted a ocean current pilot project that have been successfully (technically) obtained a "proven design”. Energy utilization of ocean current in the Nusa Penida Strait is merely for lighting public facilities. The presence of power plant have given light to 25 street lamps that installed in Toyopakeh village. This study aimed to (1) identify benefit which Toyopakeh village community perceived, (2) analyze the opportunity and estimate the value of willingness to pay (WTP) community of Toyopakeh village for management of power plant. The economic and sosiocultural benefit perceived by Toyopakeh village community in the night are increasing works effectively for seaweed strappers, stalls can opened over night, easier to moored jukung and speedboat, ship monitoring, load and unloading, fishing, and ashes disposal. Citizens with high or low income had similar opportunity readiness. Citizens with high education had opportunity WTP 1.291 point more than not ready to pay. Based on Turnbull estimator distribution, the mean WTP value was at 7 894.695 IDR (0.56 US $) and 10 641.891 (0.76 US $) range.

Abstract: One of the considerations many power plants today is whether they can get more power out of their existing equipment especially generator. However, it is required design review and feasibility study in order to extend the operating life and increase the capability and reliability. In this study, analysis of magnetic field was performed due to power uprating in order to prevent a saturation of the magnetic field in the core laminate which can lead to the emergence of heat concentration. Based on the results of magnetic analysis using finite element, there are no saturation of the magnetic field in the core lamination which can lead to the magnetic saturation and heat concentration, both for existing and uprating conditions.Therefore, the increasing a design margin on the generators from the current design of the margin of 471,000 kVA to 494,550 kVA with the 0.85 power factor will not pose a problem as long as all of the following recommendations can be implemented. Although it is predicted, there will be no saturation and hotspots on the generator, but the risk of temperature rise due to the uprating should be reduced by replacing the stator winding using the Full Class F Insulation which is resistant to temperatures up to 155 °C.

Abstract: The failure of large generators in generating stations and industrial plants is mainly caused by the failure of the stator winding insulation. The combination of electrical, mechanical and thermal stresses that are accumulated by the number of start-stop times and operating hours can reduce the residual dielectric voltage as the main cause of the deterioration on the insulation. In this study, the remaining life assessment of the generator stator insulation was conducted based on the functional relationship between stresses and remaining dielectric voltage in the worst and average cases. The case study was conducted on the fourth of generator unit in SURALAYA Coal Fired Power Plant in Indonesia that had the service life of over 25 years. To validate the assessment results, partial discharges (PD) test was performed on the stator coils of the generator. Based on the results of evaluation, it was found that the remaining life of the fourth of generator insulation at the worst case had been come to end. For the average case, the remaining life of insulation for Unit 1 and Unit 2 was 12 year, while for Unit 3 and 4 was 17 year. Then from the validation results using the PD test, there was an evidence of the discharging of voids or delamination within the insulation, where the internal discharging was seen to be the most dominant factor from the discharge pattern. However, the PD magnitudes were still within reasonable limits, where the magnitude of the maximum discharge was 3,500 pC for the U phase, while in the V and W phase was 7000 pC, hence it was not categorized as an anomaly.