bluuebunny/crossref_metadata_2025_split huggingface dataset:
Assessment of the Combustion Behavior of a Pilot-Scale Gas Turbine Burner Using Image Processing
Authors: De Giorgi Maria Grazia , Sciolti Aldebara , Campilongo Stefano , Ficarella Antonio 
Published: November 2014

Experimental investigations were performed on a non-premixed liquid fuel-lean burner. The present work aims to the development of a methodology for the recognition of flame instability regimes in industrial and aeronautical burners. Instability, in fact, is an unpleasant aspect of combustive system that negatively impacts on combustion efficiency. The online monitoring of the occurrence of instability conditions, permits to adjust combustion parameters (as fuel or air mass flow, temperature, pressure, etc.) and to stabilize again the flame.
High speed visualization systems are promising methods for on-line combustion monitoring.
In this study two high speed visualization systems in the visible range and in the infrared spectral region were applied to characterize combustion efficiency and flame stability.
Different processing techniques were used to extract representative data from flame images.
Wavelet Decomposition and Spectral analysis of pixel intensities of flame images were used for feature extraction. Finally a statistical analysis was performed to identify the most unstable regions of the flame by the pixel intensity variance.
Effects of Increased PRB Coal Consumption on the Aerodynamic Stability of Induced Draft Fans
Authors: Washington DeVon A. , Lewis James B. 
Published: November 2014

This study examines the upgrade of two forward-curved centrifugal induced draft fans, to support fuel blends with greater fractions of PRB coal for a 160 MWe generating unit. After a post installation event, an audible periodic low frequency vibration in the breeching was noticed at loads ranging from 75–95 MWe. A detailed investigation was conducted which included fluid dynamic and vibration analyses of the fan and system, as well as an assessment of the fan and motor performance characteristics.
Results of the analyses revealed system resistances which generated operating points in the stall region on the fan performance curve. Non-uniform fan inlet flow distributions were characterized by axial and transverse distortion parameters. Data showed relatively high transverse distortion parameters over the affected load range with the maximum of 20.5% distortion occurring at 95 MWe; with a corresponding breeching vibration frequency approximately four-thirds shaft speed.
Based on the data obtained and observed system behavior, it was determined the phenomenon responsible for the flow-induced vibration was the onset of rotating stall. The magnitude of the pressure pulses associated with this low frequency vibration is capable of causing fatigue damage to large ductwork and producing unwanted acoustic emissions. In light of the large number of similar conversions performed throughout industry and increases in partial-load operation, the accurate diagnosis of such phenomenon is vital for reliable plant operations. This work summarizes an effective and practical methodology for making such evaluations, while addressing issues of fan performance and system effects.
Understanding the Reactive Power Problem and a Mechanical Solution Using Peaking or Retired Generators
Authors: Attix Randall M. , Chamberlin D. M. 
Published: November 2014

Reactive power is an unwanted but unavoidable part of alternating current electric power delivery systems. Governed by the laws of physics, it occurs due to the inherent nature of the components of these systems. This article develops an understanding of reactive power and the control of it to reduce its adverse effects and to improve the efficiency of an electric power delivery system.
The article begins by identifying and representing electric power circuit components, real power, and reactive power. These are then mathematically shown how they interact and affect the power delivery system.
Control and mitigation of the effects of reactive power are then developed with emphasis on mechanical solutions using rotating machines. In particular, peaking or retired generators are identified for use as rotating condensers as well as new installations. A description of the gear type synchronous self-synchronizing (SSS) overrunning clutches used to connect and dis-connect a generator from the peaking prime mover or the retired generator from a starting system is included.
Maintaining High Energy Piping Integrity With Unit Specific Strategic Planning
Authors: Hamblin-Smoske Pamela 
Published: November 2014

High-energy piping systems are essential to the safe and cost-effective operation of power plants. The propensity for piping failures increases with the age of the systems involved. Prolonged operation, particularly at elevated temperatures, may result in metallurgical degradation which in-turn increases the potential for cracking and crack propagation until a final failure stage is reached by the component. As a result, power plant operators have become increasingly cognizant of the importance of condition assessment evaluations for high-energy piping systems.
Power plant operators are faced with specific challenges to maintain the integrity of their high energy piping systems including the reduction of onsite engineers, aging workforces, equipment, and the need to remain competitive in a challenging global energy market. Plant managers are routinely faced with the complex task of evaluating the current condition of their equipment, forecasting outage budgets and schedules, and performing risk assessments. Additionally, insurance companies are increasingly requiring inspection and maintenance records that are not always up-to-date or readily available.
The solution to strategically maintaining the integrity of high-energy piping systems involves taking a comprehensive approach to piping management utilizing unit specific operational training, advanced data management, strategic inspection, maintenance and replacement prioritization. Implementing this comprehensive approach has resulted in avoiding both catastrophic and leak type failures for plant managers that have adopted this strategy. Implementing a unit specific, targeted plan enables utility owners and operators to succeed in today’s competitive market by increasing the unit’s reliability and availability without sacrificing safety or environmental standards.
Thielsch Engineering, Inc. hosts over 30 years of advanced engineering experience and provides extensive services to more than 150 power plants each year. Our firm is also the creator and proprietary owners of the 4 SYTE System Strategies that is currently operating in more than 60 power plants throughout the U.S. and Canada. We are an employee-owned company with 425 partners who are dedicated to best practices and customer service is a priority. Thielsch has offices in Rhode Island, Ohio, Texas and Florida.
Flue Gas Desulfurization Wastewater Treatment for Coal-Fired Power Industry
Authors: Pakzadeh Behrang , Wos Jay , Renew Jay 
Published: November 2014

The United States Environmental Protection Agency (USEPA)’s announcement that it will revise the effluent limitation guidelines for steam electric power generating units could affect not only how power plants use water, but also how they discharge it. The revised guidelines may lower discharge limits for various contaminants in flue gas desulfurization (FGD) wastewater including mercury, selenium, arsenic, and nitrate/nitrite. Although the specific details of the guidelines are unknown at present, the power industry is evaluating various technologies that may address the new effluent limitation guidelines and promote water conservation. Moreover, the power industry is looking for avenues to increase water usage efficiency, reuse and recycle throughout its plant processes. Final rule approval is expected by the middle of 2014 and new regulations are expected to be implemented between 2017 and 2022 through 5-year NPDES permit cycles. discharge limits for various contaminants including arsenic, mercury, selenium, and nitrate/nitrite [1]. These pollutant limits may be below the levels achievable today with conventional treatment [2].
A growing interest exists in zero liquid discharge (ZLD) facilities and processes in power plant operations. Potentially stringent discharge limits along with water conservation and reuse efforts are two of the major drivers to achieve ZLD. Potential pollutant levels are so low that ZLD may be the best option, if not an outright requirement [1].
Thermal ZLD systems have been the subject of increased interest and discussion lately. They employ evaporating processes such as ponds, evaporators and crystallizers, or spray dryers to produce a reusable water stream and a solid residue (i.e. waste). Evaporators and crystallizers have been employed in the power industry for a number of years. However, typical A growing interest exists in zero liquid discharge (ZLD) facilities and processes in power plant operations. Potentially stringent discharge limits along with water conservation and reuse efforts are two of the major drivers to achieve ZLD. Potential pollutant levels are so low that ZLD may be the best option, if not an outright requirement. A key disadvantage of thermal ZLD is its high capital cost. One way to reduce this cost is to pre-treat the liquid stream using innovative membrane technologies and reverse osmosis (RO).
Closed-Form Stress Intensity Factor Solutions for Circumferential Through-Wall Cracks in Cylinder
Authors: Shim Do-Jun , Xu Steven , Lee Darrell 
Published: November 2014

The stress intensity factor (SIF) solutions for circumferential through-wall cracks (TWCs) in cylinders are used for various fracture mechanics analyses. For example, it can be used to calculate the crack growth rate for stress corrosion cracking and to calculate the elastic J value which is needed to obtain the total J value for crack stability calculations. Thus, numerous SIF solutions have been published for circumferential TWCs in cylinders under axial tension and global bending. However, recently, it has been indicated that there is a need (e.g., for xLPR software code and ASME BPV Code Case N-513) to expand the solutions to wider ranges of crack lengths and cylinder geometries.
In this paper, solutions from Lacire et al., API 579-1/ASME FFS-1 and Zang (SINTAP) were compared against results from independent finite element (FE) analyses performed by the authors. From these comparisons, it was demonstrated that the Zang (SINTAP) solution provided the most accurate results. Hence, additional FE calculations were performed to expand the Zang (SINTAP) solution to cover Ri/t between 2 and 100 and crack length between 1% and 85% of the cylinder circumference. Furthermore, for practical applications, closed-formed solutions were developed for both axial tension and global bending loads. These new solutions were planned for use in the xLPR software code and ASME BPV Code.
Preliminary Piping Sizing and Pressure Pulsation Evaluation
Authors: Passeri Marco , Generosi Stefano , Bagagli Riccardo , Maggi Carmelo 
Published: November 2014

LDPE production developments require processing equipment with increased capacities and existing applications uprating. They include large reciprocating compressors with several cylinders operating at very high pressures. Selection of piping size, as these special components have very long delivery time, including reactors and intercoolers, requires a careful analysis to be performed at an early stage of a project to properly estimate the costs. A preliminary evaluation should be made during the bid stage using compressor data sheet and P&I diagram. A specific pre-study linked to compressor sizing program can be used for preliminary cost estimation.
Prior to piping purchase order issue, based on the first issue of real layout around compressor, the above evaluation has to be confirmed by a preliminary pulsation study.
Once the plant arrangement will be finalized, the final acoustic study will have to be performed. Usually such study will only result in minor adjustments to the design not involving the piping size.
STYLE Project: A Large Scale Ductile Tearing Experiment on a Cladded Ferritic Pipe
Authors: Moinereau Dominique , Le Delliou Patrick , Keim Elisabeth , Nicak Tomas 
Published: November 2014

Within the framework of the FP7 European project STYLE, a large scale experiment has been performed at EDF on a cladded ferritic pipe. The objective of such an experiment was to investigate transferability of material properties from small specimens to large scale components.
The large scale experiment involves applying 4-point bending under displacement control at room temperature to a clad ferritic steel pipe with an internal surface crack. The goal of the experiment is to initiate ductile crack growth and track the resulting stable crack growth until the surface flaw fails by producing a through-wall crack.
The test specimen is representative from a surge line consisting of a clad ferritic pipe with an outer diameter of 420 mm, length of 520 mm, and base metal wall thickness of 31 mm, with an internal austenitic stainless steel cladding layer of thickness 5 mm. The base metal is a low alloy 20MnMoNi55 steel (corresponding to the specifications of an SA 508 Grade 3, Class 1 steel), and the necessary extensions are made of a high strength ferritic steel.
A wide range of instrumentation was implemented to provide data for mock-up behavior understanding and detect the ductile tearing initiation during the test.
The test has been conducted with full success on the EDF 4 point bending test facility. After the experiment, samples have been taken from the mock-up for full SEM fractographic examinations of the fracture surface for identification of failure modes.
The present paper describes the large scale experiment and presents the main experimental results and data. A synthesis of SEM fractographic examinations is also presented, to better understand the rupture behavior during the test.
A Case Study in Temper Embrittlement of Fluidized Catalytic Cracking Components
Authors: Bowen Matthew , Newell William F. , Penso Jorge 
Published: November 2014

As described in API RP 571, temper embrittlement is the reduction in toughness due to a metallurgical change that can occur in some low alloy steels as a result of long term exposure in the temperature range of about 650°F to 1070°F (343°C to 577°C). The loss of toughness is not evident at operating temperatures; however, equipment that is temper embrittled may be susceptible to brittle fracture during start-up and shutdown. 2.25 Chromium 1 Molybdenum steel used in the petrochemical industry is known to be susceptible to temper embrittlement. Most guidance to prevent temper embrittlement is oriented to heavy wall hydroprocessing reactors.
In this work, a case history is presented where Fluidized Catalytic Cracking (FCC) components less than one inch in thickness exposed to temperatures in the 900°F to 1000°F (482°C to 538°C) range experienced temper embrittlement.
Metallurgical analysis that included chemical analysis, microstructure observation, and charpy impact testing at different temperatures before and after heat treatment helped to identify the embrittlement cause.
Several considerations to mitigate the risk in the short term including inspection, definition of minimum metal temperature to prevent brittle fracture, fitness for service, and modification of operational procedures, as well as long term considerations, including pipe component replacement, are described. Additional work regarding the selection of filler metals, welding procedure qualification tests that include step cooling tests, and learning that included bead sequence and heat input controls are also described.
Applicable API RP 934-A [Ref. 6] recommendations were incorporated into the project specification for this work, such as the consideration of chemical restrictions for this alloy, not only for heavy wall applications but also for thinner wall applications working in the temper embrittlement range.
Tests on SENT Specimens to Study Geometry Effects in the Brittle to Ductile Transition
Authors: Le Delliou Patrick , Geniaut Samuel 
Published: November 2014

The accurate prediction of ductile fracture behaviour plays an important role in structural integrity assessments of critical engineering structures under fully plastic regime, including nuclear reactors and piping systems. Many structural steels and aluminium alloys generally exhibit significant increases in fracture toughness, characterized by the J-integral, over the first few mm of stable crack extension (Δa), often accompanied by large increases in background plastic deformation. Conventional testing programs to measure crack growth resistance (J–Δa) curves employ three-point bend, SEN(B), or compact, CT. However, laboratory testing of fracture specimens to measure resistance curves (J–Δa) consistently reveals a marked effect of absolute specimen size, geometry, relative crack size (a/W ratio) and loading mode (tension vs. bending) on R-curves. These effects observed in R-curves have enormous practical implications in defect assessments and repair decisions of in-service structures under low constraint conditions. Structural components falling into this category include pressurized piping systems with surface flaws that form during fabrication or during in-service operation.
This paper presents the on-going work to study geometry effects (e.g. triaxiality effects) in the brittle to ductile transition of carbon-manganese steels, the basic idea being to compare the results obtained on these specimens with the results obtained on CT specimens.
A preliminary program was previously conducted at room temperature using deeply notched specimens (Le Delliou, 2012). Finite element computations were made to optimize the specimen shape and to develop the η-factor, the shape factor F (to compute K) and the normalized compliance μ.
For the present program, new specimens have been machined with shallower notches (a/W = 0.4), to get a0/W = 0.5 after fatigue pre cracking. Fatigue pre cracking was conducted in 4-point bending to avoid damaging the back of the notch. Moreover, the specimens have been cut in the TS (Transverse-Short) direction of the plate to get lower toughness properties, and less plasticity during the tests.
Tests at room temperature have been conducted first to validate the revised test procedure. Then, the SENT specimens have been tested at −100°C, −60°C, and −40°C, together with CT specimens.
Fatigue Monitoring Approaches for Power Plants
Authors: Jouan Benoît , Bergholz Steffen , Rudolph Jürgen 
Published: November 2014

Modern state-of-the-art fatigue monitoring approaches gain in importance not only as part of the ageing management of nuclear power plant components but also in the context of conventional power plants and renewables such as wind power plants. Consequently, lots of operators have to deal with demanding security requirements to ensure the safe operation of power plants and to cope with plant lifetime extension (PLEX) related issues.
AREVA disposes of a long tradition in the development of fatigue and structural health monitoring solutions. Nuclear and conventional power plant applications require the qualified assessment of measured thermo-mechanical loads. The methodology is transferable to mechanical loading conditions such as those of wind energy plants. The core challenge is the identification and qualified processing of realistic load-time histories. The related methodological requirements will be explained in detail.
In terms of the nuclear industry, the ageing management of power plant components is nowadays a main issue for all actors: states, regulatory agencies, operators, designers or suppliants. As regards fatigue assessment of nuclear components stringent safety standards imply the consideration of new parameters in the framework of the fatigue analysis process:
• new design fatigue curves, consideration of environmental fatigue (EAF) parameters and
• stratification effects.
In this general context AREVA developed the integral approach AREVA Fatigue Calculation (AFC) with new tools and methods in order to live up to operators’ expectations: Simplified Fatigue Estimation (SFE), Fast Fatigue Evaluation (FFE) and Detailed Fatigue Check (DFC). Based on real measured thermal loads and superposed mechanical loads the Fast Fatigue Evaluation (FFE) process allows a highly automated and reliable data processing to evaluate cumulative usage factors of mechanical components. Calculation and management of results are performed within the fatigue assessment software FAMOSi (FAatigue MOnitoring System integrated), thus impact of operating cycles on components in terms of stress and fatigue usage can be taken into account in order to plan optimized decisions relating to the plant operation or maintenance activities.
This paper mainly describes the fatigue and structural health methodologies developed within the AREVA Fatigue Concept (AFC).
Development of Fiber-Optic Probes to Measure Two-Phase Flow Dynamic Parameters in Support of Flow-Induced Vibration Studies
Authors: Pettigrew M. J. , Besner B. , Mureithi N. W. , Lafrance T. , Patrick J. M. 
Published: November 2014

Flow-induced vibration in two-phase flows requires the knowledge of flow regime and detailed flow characteristics. This paper outlines the development of fiber-optic probes to measure void fraction, local flow velocity and characteristic size (i.e., bubble diameter) of the two-phase mixture. The principle of operation of such probes is based on the difference in index of refraction between the liquid phase and the gas phase when in contact with a fiber-optic probe supplied with a laser light. The reflected signal levels for the gas phase and the liquid phase are very different thus providing a reliable measure of void fraction.
The paper describes the development of fiber-optic probes for measurements of internal two-phase flow in pipes and of external flow across a tube bundle. The use of double probes allows the measurements of local flow velocity and bubble size. Some detail measurements of flow in the gap between tubes in cross flow are presented. The fabrication of the very small and fragile probes required much development effort. The paper describes the difficulties and the solutions to assure good quality probes. Some data processing and data interpretation issues are also discussed.