bluuebunny/crossref_metadata_2025_split huggingface dataset:
Reliability, Availability, Maintainability (RAM) for Wind Turbines
Authors: Kumar Nikhil , Rogers David , Burnett Thomas D. , Sullivan Eric , Gascon Martin 
Published: September 2017

Wind based electric generation is one of the fastest growing energy sources in the world. With rapid development of wind farms, many challenges have emerged with respect to the reliability and availability of the in-service equipment. Additionally, with increasing size of wind turbine blades, both onshore and offshore, the serviceability and maintainability of the equipment poses its own unique challenge. There is also an inherent risk from the economics of energy production, which dictates that low-cost manufacturing methods are employed to produce cost-effective machines.
In our experience, there are additional risks associated with supply chains and limited availability and understanding of damage mechanisms and reliability data of the myriad manufacturers and models of turbines, blade design and associated equipment. Failure of different components results in different outage times and therefore impact operational and maintenance (O&M) costs in different ways. Achieving high availability targets requires a robust O&M plan.
The authors will highlight operational risks of large wind turbines and methodologies to improve reliability and availability for wind farms.
Can Propane Displace Diesel as a Fuel for Power Generation?
Authors: Welch Michael , Patel Rajan 
Published: September 2017

Access to electricity is a key necessity in today’s World for economic growth and improvements in quality of life. However, the global challenge is addressing the so-called Energy Trilemma: how to provide secure, affordable electricity while minimizing the impact of power generation on the environment. The rapid growth in power generation from intermittent renewable sources, such as wind and photovoltaics, to address the environmental aspect has created additional challenges to meet the security of supply and affordable electricity aspects of this trilemma. Fossil fuels play a major role in supporting intermittent renewable power generation, rapidly providing the security of supply needed and ensuring grid stability.
Globally diesel or other fuel oils are frequently used as the primary fuel or back-up fuel for fossil-fueled power generation plants at all scales, from a few kiloWatts to hundreds of MegaWatts, and helps provide millions of people with secure electricity supplies. But diesel is a high polluting fuel, emitting high levels of carbon dioxide (CO2) per unit of fuel input compared to natural gas, as well as high levels of combustion contaminants that are potentially hazardous to the local environment and human health. Additionally, diesel can be a high cost fuel in many countries, with imports consuming significant portions of sometimes scarce foreign currency reserves.
Most observers consider that natural gas is the ‘fuel of choice’ for fossil power generation due to its reduced CO2 emissions compared to coal and diesel. However, access to gas supplies cannot be guaranteed even with the increased availability of Liquefied Natural Gas (LNG) and Compressed Natural Gas (CNG). Additionally where natural gas is available, operators may opt for an interruptible gas supply contract which offers a lower tariff than a firm gas supply contract, therefore there is a need for a back-up fuel to ensure continuous power supplies. While traditionally diesel or Heavy Fuel Oil (HFO) has been used as fuel where gas is not available or as a back-up fuel, propane offers a cleaner and potentially lower cost alternative. This paper compares the potential economic, operational and environmental benefits of using propane as a fuel for gas turbine-based power plants or cogeneration plants.
Evaluation of the Tube to Tubesheet Joining Process in an AL6XN® Feedwater Heater
Authors: Svensson Eric , Catapano Michael 
Published: September 2017

Type 304 austenitic stainless steel is the most common tube material utilized for nuclear feedwater heaters, however, some utilities have experienced problems with Stress Corrosion Cracking (SCC), especially when they utilize brackish cooling water and have experienced condenser tube leaks. This has forced some utilities to explore other options when it comes to high pressure feedwater heaters (HP FWH) tubing materials. AL6XN® is considered a “super” stainless steel that is resistant to (SCC), however, it is not immune (AL6XN is a trademark of ATI Technologies).
Based on the relative inexperience and unknowns related to the use of AL6XN tubing in high pressure, nuclear feedwater heater applications, a detailed mock-up procedure was outlined as part of the replacement heater specification which would allow the evaluation of the tube to tubesheet joining processes. Since AL6XN can still be affected by SCC; steps were taken in order to minimize the imposed stress levels and any potential for the inadvertent inclusion of contaminants during the fabrication steps at the tube mill and at the feedwater heater Manufacturer’s shop. The desire to minimize stresses also applies at the tube to tubesheet joint, therefore, it was desired not to stress the tube more than absolutely necessary in achieving a reliable, leak tight joint. The mock-up details and procedures were therefore generated with these objectives in mind, so as to give consideration for the ability to check different configurations in order to determine the most efficient tube to tubesheet joining process.
Several tubes in the mock-up were subjected to a pull out test in order to quantify the joint strength in the different configurations. The mockup was then sectioned and inspected under a digital microscope to verify intimate contact between the tube and the tubesheet. Once the optimal procedure was identified, four identical HP FWHs were constructed utilizing AL6XN tubing. During heater production, over 30,000 tube ends were expanded, however, two tubes were identified to have failures as part of the tube expansion process.
This paper shall describe the procedures utilized in developing and analyzing the tubesheet mock-up as well the actions taken to identify the root causes of the tube failures.
A Comparative CFD Simulation Study of Two-Channel and Three-Channel Claus Reactors
Authors: Huang Shan , Zhou Qulan , Li Na , Tian Fangyong , Zhang Lisheng 
Published: September 2017

The Claus reactors is widely used to recover elementary sulfur from hydrogen sulfide that is contained in fresh natural gas. It involves thermal oxidation of hydrogen sulfide and its reaction with sulfur dioxide to form sulfur and water vapor. To improve the efficiency of the process, we built two kinds of 3-dimensional Claus reactor models to explore the key factors that affect the combustion reactions. The two-channel Claus reactor consisted of an air channel and an acid gas channel (60% H2S, 33% CO2, 7%H2O) while the three-channel Claus reactor consisted of two air channels and an acid gas channel (60% H2S, 33% CO2, 7%H2O). The two-channel model was built according to the devices used in the factory while the three-channel model was improved by us from the two-channel model. In both the two models, air and acid gas turned into swirling flow in their channels respectively before their mixture. Then air and acid gas mixed and burned at the throat of the models. The most remarkable difference between the two kinds of Claus reactors was that the three-channel reactor had an additional inner air channel inside the acid gas channel that can be helpful to the mix of the acid gas and air. The second difference was that the two kinds of reactors had different deflectors to swirl in the flow fields. In this study, we compared the flow fields and concentration fields of the two kinds of Claus reactors by using a computational fluid dynamics (CFD) tool.
The simulation results indicated that the swirling intensity and the mix intensity played an important role in the combustion reactions. The efficiency of sulfur recovery in Claus reactors increased with an increase of the swirling intensity or the mix intensity. The stronger the swirling intensity or the mix intensity was, the sooner the mixture of air and acid gas reached to the best stoichiometric ratio. The three-channel reactor had a better performance than that of the two-channel reactor due to the additional inner air channel which can strengthen the mix of the acid gas and air from the inside of the acid gas. Moreover, the helix deflectors in the three-channel reactor had a better swirling performance than that of the vane deflectors in the two-channel reactor. From the comparison of the two models, we can obtain a way to improve the process of elementary sulfur recovery in the industry, which can be helpful to reduce pollution emissions and improve economic performance.
Enhancement of an Equipment Reliability Program With Smart, Connected Power Plant Assets
Authors: Reid Michael , File Tony 
Published: September 2017

The U.S. electric utility industry continues to undergo dramatic and accelerating transformation. Reliability and resiliency are a key focus. A number of important issues including cyber and physical security challenges, aging infrastructure, and low natural gas prices continue to be of concern. Significant advances in technology, and prolonged regulatory uncertainty are also contributing factors.
Electric utilities are now making substantial investment in renewable resources and other technologies needed for renewables integration. This means a reduction in investment in generation assets and an increase in the transmission and distribution grids. There is also increased investment in providing customers with solutions to lower their costs, reduce their carbon footprint and provide control over their energy management.
The transformation ultimately demands significant increases in power plant generation operating capabilities and higher levels of equipment reliability while reducing O&M and capital budgets. Achieving higher levels of equipment reliability, with such tightening budget and resource constraints, requires a very disciplined approach to maintenance and an optimized mix of the following maintenance practices:
• Preventative (time-based)
• Predictive (condition-based)
• Reactive (run-to-failure)
• Proactive (combination of 1, 2 and 3 + root cause failure analysis)
Preventive maintenance (PM) is planned maintenance actions taken to ensure equipment is capable of performing its required functions. PM tasks are generally time-based, depending on the availability of condition monitoring data through a predictive maintenance (PdM) program.
Traditionally, PdM is largely performed by maintenance technicians in the field with handheld devices. Resource constraints usually mean that often weeks or even months elapsed between readings on the same piece of equipment. This approach has limitations with data volume, velocity, variety, and veracity.
Significant recent advances in sensor and technology associated with the Industrial Internet of Things (IIoT) have enabled the transformation of critical power plant assets such as steam turbines, combustion turbines, generators, and large balance-of-plant equipment into smart, connected power plant assets. These enhanced assets, in conjunction with analysis and visualization software, provide a comprehensive on-line conditioning monitoring solution that enables both a reduction in time-based PM tasks and also automation of PdM tasks.
This paper describes an approach by Duke Energy to apply smart, connected power plant assets to greatly enhance its fossil generation equipment reliability program and processes. It will outline the value that is currently being realized and will also examine additional opportunities.
Structural Analysis of a Novel Ducted Wind Turbine
Authors: Menon Shruti Mohandas , Goudarzi Navid 
Published: September 2017

Renewable energy technologies offer a competitive cost of energy values in large-scale power generations compared with those from traditional energy resources. In 2015, residential and commercial buildings consumed 40% of total US energy consumption. Short and long-term plans have been developed to further employing wind energy technologies for electricity generation. However, there is a significant gap in developing reliable utility-scaled distributed wind energy converters. Employing novel low-cost wind harnessing technologies in these sectors supports the renewable-energy expansion plans.
A novel ducted wind turbine technology, called Wind Tower, for capturing wind power is designed and developed in earlier works. In this work, the Wind Tower structural analysis is conducted to obtain insights to the required materials and optimum components’ dimensions at an expanded range of wind flow regimes. A stable and robust design addresses the need for developing an optimum solution to obtain a maximum output power generation at a minimum cost of energy. It will lead to a maximum return on investment. The results demonstrate a superior structural performance of the Wind Tower Technology. It withstands pressure loads from high wind speed when it is installed as a standalone structure.
A Simulation Model for the Performance Enhancement of Turbocharged Diesel Engine
Authors: Ahmad Farrukh , Aziz Imran , Shah Samiur Rahman 
Published: September 2017

Diesel engines are widely used throughout the world in the transportation and industrial sector. Over the years, engineers and researchers have made continuous efforts to maximize the efficiency of the diesel engine, but there is still room for improvement. By maximizing the efficiency we can not only reduce the fuel consumption of engine, but can also add positively to the environment by reducing the emissions from the engine.
In the present research a simulation model for the optimization of the performance of a diesel engine’s has been developed using the cylinder to cylinder approach. Physical, empirical and thermodynamic relations are used to setup the model in MATLAB. The model can predict the backflow through the valves based upon pressure difference across the valves. Multi event fuel injection technique is employed using main injection and pilot injection. The turbocharger is investigated with and without intercooler to see the effect on engine performance. The simulated results are in good agreement with already presented experimental results.
A study has been performed to analyze the effect of variation of different parameters on the efficiency of the compression ignition engine. The parameters analyzed are bore to stroke ratio, compression ratio, equivalence ratio, injection timing variation (advance, retard), inlet charge heating and turbo-charging. By using the developed technique it is easier to make decisions regarding efficiency optimization in the design phase of the engine. The testing time and cost associated with the engine can also be reduced. The study provides a thorough insight on the effect of parametric variation on engine efficiency.
Experimental Study on the Density Wave Oscillations of Supercritical Water in Vertical Upward Tubes
Authors: Kong Xiangfei , Liu Xin , Guo Kaikai , Feng Yuan , Li Huixiong 
Published: September 2017

Supercritical and ultra-supercritical pressure boilers have been widely used in China because of its advantages of high capability, high thermal efficiency and low pollutants emission. In view of the high working parameters and complicated working conditions of such boilers, safe and stable operations of these boilers have become the focus of attention of related researchers and engineers for many years. As one of the most important phenomena that may occur in thermal power plants, flow instabilities of water in boilers’ water-cooled wall may result in heat transfer deterioration, thermal fatigue of pipes and even breakdown of the supercritical units, and have thus attracted much attention of developers and researchers of the boilers.
However, due to difficulties in carrying out experiments on the density wave oscillation of water under supercritical pressures, the related experimental data is very rare, and moreover, the characteristics of density wave oscillations of water under supercritical pressures has not been well understood.
A series of experiments have been conducted on the density wave oscillation of water flowing at supercritical pressures in a 6-m long vertical upward tube with 20.0-mm internal diameter. The experimental parameters cover the pressures from 23 to 27 MPa, the mass fluxes from 300 to 600 kg·m−2·s−1, and the heat fluxes from 225 to 500 kW·m−2. Three types of density wave oscillation were found in the present study: 1) stable periodic density wave oscillation, 2) attenuated density wave oscillation, 3) divergent density wave oscillation. Effects of pressures, mass fluxes and heat fluxes on the density wave oscillation were analyzed. With the increase in pressures and mass fluxes, the density wave oscillation of supercritical pressure water can be postponed, and is difficult to occur. And the density wave oscillation will be triggered and enhanced by increasing the heating flux. The mechanism of density wave oscillation of supercritical pressure water in tubes was also analyzed, and a dataset was established for the verification of related numerical calculations and modeling.
Experimental Investigation of Activation Solution for On-Line Activating SCR-DeNOx Catalyst
Authors: Chen Dong Lin , Ye Tuo , Zeng Xi 
Published: September 2017

Currently, SCR-DeNOx technology of flue gas has been widely applied in coal-fired power plants in China for its higher denitrification efficiency, lower ammonia escape and more stable operation performance. In order to overcome the shortages of the off-line method, an on-line method based activating was proposed. However, many key technologies also need to be researched that one of them is a cheap and efficient activating solution. First, activating solutions were prepared by means of single factor and experimental investigations of catalysts activation were conducted. Second, impacts of the catalysts, which were activated by the above mentioned solutions, NO removal and activity were tested and compared with that of the inactivated catalyst. The effect of active components (vanadium, tungsten, molybdenum, oxalic acid) and flue gas conditions on the activation of catalyst were investigated. Then, analysis of these catalysts by scanning electron microscopy (SEM), the specific surface area (BET), Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD) were conducted. Finally, an ideal activating solution was found out through the analysis of the efficiency of denitrification and the macro and micro changes from catalysts.
The following conclusions were obtained through the above mentioned activation experiments: 1) NO removal by activated catalysts is higher than that of inactivated catalyst; the De-NOx efficiency can be up to 99% in the following conditions: the reaction temperature (370 °C), the proportion of the active solution component (1.0%-V, 9%-W, 6%-Mo), the oxygen concentration (4%-O2) and the ratio of ammonia and nitrogen (NH3:N2 = 1:1); 2) the airspeed and the initial concentration of NO had little influence on catalyst activation; 3) the specific surface area and pore size of the activated catalyst were significantly increased that the active components of the catalyst surface were effectively added. Our investigation results to illustrate that the enhancement of active components, broadening of acid sites distribution, and including the surface labile oxygen and small pores opening to be the reason for high denitrification efficiency.
Effects of Cooling System Operations on Withdrawal for Thermoelectric Power
Authors: Clement Zachary , Fields Fletcher , Bauer Diana , Tidwell Vincent , Shaneyfelt Calvin Ray , Klise Geoff 
Published: September 2017

A new dataset released by the Energy Information Administration (EIA) — which combines water withdrawal, electricity generation, and plant configuration data into a single database — enables detailed examination of cooling system operation at thermoelectric plants at multiple scales, most importantly at the unit level. This dataset was used to explore operations across the population of U.S. thermoelectric plants, leading to the conclusion that roughly 32% of all thermoelectric water withdrawal occurs while power plants are not generating electricity. Based on interviews with industry representatives, a unit’s location on the dispatch curve will largely dictate how the cooling system is operated. Peaking plants and intermediate plants might keep their cooling system running to maintain dispatchability. Other considerations include minimizing wear and tear on the pumps and controlling water chemistry.
This observation has implications for understanding water use at thermoelectric plants, policy analysis, and modeling. Previous studies have estimated water use as a function of cooling technology, fuel type, prime mover, pollution controls, and ambient climate (1) or by calculating the amount of water that is thermodynamically necessary for cooling (2). This, however, does not capture all the water a plant is withdrawing simply to maintain dispatchability. This paper uses the new data set from EIA and interviews with plant operators to illuminate the role cooling systems operations play in determining the amount of water a plant withdraws.
Metabolism and Whole-Body Fat Oxidation Following Postexercise Carbohydrate or Protein Intake
Authors: Andersson-Hall Ulrika , Pettersson Stefan , Edin Fredrik , Pedersen Anders , Malmodin Daniel , Madsen Klavs 
Published: September 2017

Purpose: This study investigated how postexercise intake of placebo (PLA), protein (PRO), or carbohydrate (CHO) affected fat oxidation (FO) and metabolic parameters during recovery and subsequent exercise. Methods: In a cross-over design, 12 moderately trained women (VO2max 45 ± 6 ml·min−1·kg−1) performed three days of testing. A 23-min control (CON) incremental FO bike test (30–80% VO2max) was followed by 60 min exercise at 75% VO2max. Immediately postexercise, subjects ingested PLA, 20 g PRO, or 40 g CHO followed by a second FO bike test 2 h later. Results: Maximal fat oxidation (MFO) and the intensity at which MFO occurs (Fatmax) increased at the second FO test compared to the first following all three postexercise drinks (MFO for CON = 0.28 ± 0.08, PLA = 0.57 ± 0.13, PRO = 0.52 ± 0.08, CHO = 0.44 ± 0.12 g fat·min−1; Fatmax for CON = 41 ± 7, PLA = 54 ± 4, PRO = 55 ± 6, CHO = 50 ± 8 %VO2max, p < 0.01 for all values compared to CON). Resting FO, MFO, and Fatmax were not significantly different between PLA and PRO, but lower for CHO. PRO and CHO increased insulin levels at 1 h postexercise, though both glucose and insulin were equal with PLA at 2 h postexercise. Increased postexercise ketone levels only occurred with PLA. Conclusion: Protein supplementation immediately postexercise did not affect the doubling in whole body fat oxidation seen during a subsequent exercise trial 2 h later. Neither did it affect resting fat oxidation during the postexercise period despite increased insulin levels and attenuated ketosis. Carbohydrate intake dampened the increase in fat oxidation during the second test, though a significant increase was still observed compared to the first test.