bluuebunny/crossref_metadata_2025 huggingface dataset:
Mortality caused by influenza and respiratory syncytial virus by age group in England and Wales 1999–2010
Authors: Hardelid P. , Pebody R. , Andrews N.
Published: March 2012

Please cite this paper as: Hardelid et al. (2012) Mortality caused by influenza and respiratory syncytial virus by age group in England and Wales 1999–2010. Influenza and Other Respiratory Viruses DOI: 10.1111/j.1750‐2659.2012.00345.x.

Background:  The mortality burden caused by influenza cannot be quantified directly from death certificates because of under‐recording; therefore, the estimated number of influenza deaths has to be obtained through statistical modelling.

Objective:  To estimate the number of deaths caused by influenza and respiratory syncytial virus (RSV) in England and Wales between 1999 and 2010 using a multivariable regression model.

Methods:  Generalised linear models were used to estimate weekly deaths by age group (<15, 15–44, 45–74 and 75+ years) as a function of positive influenza and RSV isolates. Adjustment was made for temperature variation (using weekly means of daily Central England temperature time series), underlying seasonal variation and temporal trends. The parameters from the model were used to predict the number of deaths caused by influenza and RSV across winter seasons.

Results:  Between 7000 and 25 000 deaths across all ages were associated with influenza in the winter periods 1999–2009. The mortality burden was the highest among the over 75 age group, among whom 2·5–8·1% of deaths were caused by influenza. The lowest number of influenza deaths was estimated for the winter 2009/2010 when pandemic influenza A/H1N1 (2009) was the predominant circulating strain. RSV accounted for 5000–7500 deaths each winter season.

Conclusions:  The model presented provides a robust and reasonable approach to estimating the number of deaths caused by influenza and RSV by age group at the end of each winter.
An assessment of prime‐boost vaccination schedules with AS03A‐adjuvanted prepandemic H5N1 vaccines: a randomized study in European adults
Authors: Gillard Paul , Caplanusi Adrian , Knuf Markus , Roman François , Walravens Karl , Moris Philippe , Dramé Mamadou , Schwarz Tino F.
Published: March 2012

Please cite this paper as: Gillard et al. (2012) An assessment of prime‐boost vaccination schedules with AS03A‐adjuvanted prepandemic H5N1 vaccines: a randomized study in European adults. Influenza and Other Respiratory Viruses DOI: 10.1111/j.1750‐2659.2012.00349.x.

Background  Long‐term persistence of immune response and safety of an H5N1 prepandemic influenza vaccine adjuvanted with AS03 (an α‐tocopherol oil‐in‐water emulsion‐based adjuvant system) was evaluated using various prime‐boost schedules that mimicked potential pandemic scenarios (NCT00430521).

Methods  Five hundred and twelve healthy adults aged 18–60 years received primary vaccination with one or two doses (0, 21 days schedule) of the A/Vietnam/1194/2004 H5N1 vaccine followed by a booster dose (A/Vietnam/1194/2004 or A/Indonesia/05/2005 strain) six or twelve months later across eight randomized groups. Immunogenicity results by hemagglutination inhibition [HI] assay, microneutralization assay, and the cell‐mediated immune response (CMI) are reported here for the four groups boosted at Month 12.

Results  A one‐dose‐adjuvanted primary administration followed 12 months later by a single‐adjuvanted booster dose containing a heterologous vaccine strain met or exceeded all US and European criteria for both strains. Increasing the interval between the first and second dose (from 21 days to 12 months) resulted in stronger cross‐reactive immune responses against the A/Indonesia/05/2005 strain. The HI antibody response against the two strains persisted for 6 months after the booster dose irrespective of the booster vaccine’s strain. The neutralizing antibody responses and the CMI observed in the study population paralleled the HI immune response. Overall, the vaccine had a clinically acceptable safety profile.

Conclusion  The H5N1 vaccine in this study allowed for flexibility in the time interval between primary and booster vaccination and the use of a heterologous strain without impacting the strength of the humoral and cellular immune response to both vaccine strains.
Single‐dose inhaled laninamivir: registered in Japan and its potential role in control of influenza epidemics
Authors: Sunagawa Satoko , Higa Futoshi , Cash Haley L. , Tateyama Masao , Uno Tsukasa , Fujita Jiro
Published: March 2012

Please cite this paper as: Sunagawa et al. (2012) Single‐dose inhaled laninamivir: registered in Japan and its potential role in control of influenza epidemics. Influenza and Other Respiratory Viruses DOI: 10.1111/j.1750‐2659.2012.00351.x.
Retinal vessel diameter can reliably be determined in minipigs using Retinal Vessel Analyser with a microscope‐mounted fundus camera
Authors: Papadopoulou Domniki N. , Mangioris George , Petropoulos Ioannis K. , Mendrinos Efstratios , Mavropoulos Anestis , Pournaras Constantin J.
Published: March 2012

Purpose:  Retinal Vessel Analyser (RVA) is a validated instrument to measure retinal vessel diameter in humans. The purpose of this study was to assess the reproducibility (inter‐observer reliability) and the repeatability (test–retest reliability) of RVA with a microscope‐mounted fundus camera to determine retinal vessel diameter in minipigs.

Methods:  Ocular fundus image from five anaesthetized minipigs was recorded in a digital videotape for approximately 5 min, under stable systemic arterial pressure and gas conditions. To evaluate the reproducibility, each one of two investigators used RVA to measure the diameter of the superior temporal retinal artery on five separate 30‐second video sequences from each minipig, which were the same video sequences for both investigators. To evaluate the repeatability, one investigator performed five measurements on a single, randomly selected, 30‐second video sequence from each minipig. The reproducibility was determined using the intra‐class correlation coefficient (ICC), and the repeatability was assessed using the coefficient of variation (COV). Bland–Altman plots were also used to assess agreement between the two investigators.

Results:  Retinal arteriolar diameter measurements with RVA in minipigs were highly reproducible. Differences between the two investigators were lower than 0.7%. The ICC was 1.00, indicating perfect reproducibility, and the mean COV was 0.18%, reflecting excellent repeatability of the measurements with RVA.

Conclusion:  Retinal vessel diameter can reliably be determined not only in humans, but also in minipigs, using the commercially available RVA apparatus and a microscope‐mounted fundus camera.
Learning curve in the Cut and Paste method for surgery of primary pterygium
Authors: Koranyi Gabor , Artzén Ditte , Wijk Tomas
Published: March 2012

Purpose:  To evaluate the learning curve for the surgery of primary nasal pterygium with conjunctival autograft using fibrin adhesive (the Cut and Paste method).

Methods:  The outcomes of the first consecutive 120 primary pterygium surgery cases for two surgeons (groups A and B) were investigated retrospectively and compared with the first (group C) and second (group D) 120 cases of GK. A and B were previously inexperienced in pterygium surgery. Outcome variables were surgery time, complications, the number and the temporal distribution of the recurrences. The statistics used were moving averages of the recurrences, Scheffé’s test of means, learning curve analysis according to Wright and logarithmic curve fitting to operation time data. The impact of age and sex on recurrences was tested using t‐tests and chi‐square tests.

Results:  The mean surgery time was 17 min for A, 13 min for B and 13 min for GK. There was a certain learning curve slope in operation time in groups A and C. The postoperative complications were few and acceptable. There were ten (8.9%) recurrences in group A, eight (6.8%) in group B, six (5.5%) in group C and five (4.6%) in group D. The temporal distribution of the recurrences did not show any learning curve. Age and sex had no significant correlation with recurrence rate or surgery time (data not shown).

Conclusions:  Our study indicates that the Cut and Paste technique is easy to learn and master. We did not find a significant learning curve regarding surgery time, recurrences or complications. In a clinical setting, it is beneficial to let a few, otherwise experienced eye surgeons learn the technique.
Advanced Combined Cycle Systems Based on Methanol Indirect Combustion
Authors: Deng Shimin , Hynes Rory
Published: March 2012

In this paper, two new combined cycle systems with/without CO2 capture based on methanol indirect combustion are developed, which have significantly higher efficiency than methanol fueled conventional combined cycle. The performance of the new systems is compared with conventional combined cycle to identify the potentials of methanol indirect combustion. The systems are modeled by using Aspen Plus™ and GTPro™. Exergy analysis and the principle of cascade utilization of chemical exergy reasonably explain the improved efficiency of the new systems. Other merits of the combined cycle system based on methanol indirect combustion are discussed and its promising commercial application aspects are pointed out.
Effect of Inclination Angle of Splitter Plate on Flow Over a Circular Cylinder
Authors: Zhang Li , Ding Lin
Published: March 2012

Two-dimensional unsteady laminar flow over a circular cylinder with an attached splitter plate was investigated numerically. To see the effect of the splitter plate length and inclination angle on the pressure distributions and vortex shedding, numerical simulations were done for moderate Reynolds numbers ranging from 100 to 500 in two different splitter plate lengths (1 and 2 diameters), and the angles between splitter plate and wake centerline was changed from 0 to 45 deg. Results indicate that the wake structure and length are dependent on the inclination angle of splitter plate. Near wake length is almost unchanged when θ>25 deg. On the other hand, circular cylinder’s drag coefficient is distinctly affected by the position of vortex. And significant local peaks of the RMS lift coefficient are obtained at θ=15 deg and 5 deg for L=1D and 2D respectively. The lift force is in one direction when the inclination angle is over a critical value. In addition, the non-dimensional Strouhal number representing the vortex shedding frequency characteristics varies as a function of the angle and has peak values at θ=20 and 5 deg for L=1D and 2D respectively. And the longer splitter plate causes more decrease in the Strouhal number for θ>15 deg.
Prediction of Coal and Biomass Co-Firing in Large Utility Boilers
Authors: Bar-Ziv E. , Steg Z. , Chudnovsky B. , Talanker A. , Kunin A.
Published: March 2012

Co-firing biomass with coal seems a relatively low cost solution to reduce greenhouse gases (GHG) and is also an effective way of taking advantage of the high thermal efficiency of large coal fired boilers. Existing coal-fired power stations can quickly be modified for biomass co-firing achieving considerable levels of renewable generation at low capital costs and low commercial risk. However, certain biomass properties may require the retrofitting of the power plants that were originally designed to operate on a particular bituminous coal. These modifications may decrease the boiler reliability and as result reduce availability and increase operation and maintenance costs. To understand these undesirable effects and determine the optimum way to co-fire biomass in IEC’s 5000 MW coal-fired boilers we studied the effect of biomass co-firing on the capacity, heat transfer surfaces, firing systems, pulverizers, fans and airheaters. We evaluated two biomass alternatives — pelletized biomass and torrefied-biomass (bio-coal) — co-fired with bituminous coals in 575 MW tangentially-fired and 550 MW opposite wall burner boilers. Boiler performance, emission and pulverizer self consumption were discussed. Considering all above aspects, we concluded that the most cost effective alternative is co-firing bio-coal with coal.
Wind Tunnel Testing of a Telescopic Blade Wind Turbine
Authors: Imraan Mustahib , Sharma Rajnish N. , Flay Richard G. J.
Published: March 2012

The reduction in cost of energy from wind turbines requires many technical contributions from all areas of Wind Energy Conversion Systems. The concept of a telescopic blade has been analyzed to improve rotor blade performance. The effect of a step change is significant for any extension. The current simulation model in WT Perf with a Prandtl tip and hub loss model over-predicts the rotor performance. The correlations developed herein for telescopic blades with step change in the blade chord are in good agreement with the experimental data. The maximum loss for a rotor blade with a step change occurs when the extension is equal to the root blade chord.
The CO2 Transcritical Power Cycle for Low Grade Heat Recovery: Discussion on Temperature Profiles in System Heat Exchangers
Authors: Chen Y. , Lundqvist P.
Published: March 2012

Carbon dioxide transcritical power cycle has many advantages in low-grade heat source recovery compared to conventional systems with other working fluids. This is mainly due to the supercritical CO2’s temperature profile can match the heat source temperature profile better than other pure working fluids and its heat transfer performance is better than the fluid mixtures, which enables a better cycle efficiency. Moreover, the specific heat of supercritical CO2 will have sharp variations in the region close to its critical point, which will create a concave shape temperature profile in the heat exchanger that used for recovering heat from low-grade heat sources. This brings more advantage to carbon dioxide transcritical power systems in low-grade heat recovery. This study discusses the advantage of carbon dioxide power system in low-grade heat source recovery by taking this effect into account. A basic carbon dioxide transcritical power system with an Internal Heat Exchanger (IHX) is employed for the analysis and the system performance is also compared with a basic Organic Rankin Cycle (ORC). Software Engineering Equation Solver (EES) and Refprop 7.0 are used for the cycle efficiency and working fluid properties calculations.
Predicting Fly Ash Accumulation in a Fossil Power Plant Flue Gas Duct Using Computational Fluid Dynamics
Authors: Pal S. , Peltier Leonard , Krasnopoler Mitchell , Knight Kelly J. , Berkoe Jonathan
Published: March 2012

During the startup of a new fossil power plant, a high level of fly ash accumulation (higher than predicted) was encountered in the flue gas ducting upstream of a fluidized bed scrubber. The level of fly ash accumulation made it necessary to manually withdraw fly ash using a vacuum truck after short periods of operation, at less than 80% maximum continuous rating (MCR). This paper presents a simple method for rapid assessment of fly ash accumulation in flue gas ducts using steady state single phase Computational Fluid Dynamics (CFD) simulation of flue gas flow. The propensity for fly ash accumulation in a duct is predicted using calculated wall shear stresses from CFD coupled with estimates for the critical shear stresses required for mobilization of settled solids. Critical values for the mobilization stresses are determined from the Shields relations for incipient motion of particles in a packed bed with given fly ash particle size and density as inputs. Solids accumulation is possible where the wall shear stress magnitude is less than the critical shear stress for mobilization calculated from the Shields relations. Predictions of incipient fly ash accumulation based on the coupled CFD/Shields relations model correlate well with plant startup field observations. Fly ash accumulation was not observed in a related physical scale model test. A separate CFD/Shields relation analysis of the scale model physical tests show that the wall shear stresses in the scale model are several times larger than the critical value required for the mobilization of the fly ash simulant. This study demonstrates that a simple steady state, single phase CFD analysis of flue gas flow can be used to rapidly identify and address fly ash accumulation concerns in flue gas duct designs. This approach is much simpler and computationally inexpensive compared to a transient Eulerian multiphase simulation of particle laden flow involving handling the dense phase in regions of ash accumulation. Further, this study shows that physical model tests will be accurate for predicting fly ash accumulation, only if, the scaling maintains the proper ratio of wall shear stress to critical remobilization stress.
Economy Analysis of Electricity Production From Hydrogen in Combination With Nuclear Power Plant
Authors: Avsec Jurij , Virtic´ Peter , Zˇagar Tomazˇ , Sˇtrubelj Luka
Published: March 2012

Efficient and sustainable methods of clean fuel and energy production are needed in all countries of the world in the face of depleting oil reserves and the need to reduce carbon dioxide emissions. Some countries are developing technologies that could be named zero carbon technologies. The presented article will show how hydrogen technologies could be implemented with renewable technologies and nuclear technology. Nuclear technology produce very cheap electricity and could produce also cheap energy like heat and vapour. This technology should be used in nuclear power plants to develop other products like hydrogen, biofuels or district heating. One of the biggest opportunities for nuclear energy technology is to produce hydrogen. Some countries like Canada and US are in preparation to build hydrogen villages. However, a key missing element is a large-scale method of hydrogen production [1–5]. As a carbon-based technology, the predominant existing process (steam-methane reforming (SMR)) is unsuitable. This paper focuses on a production of hydrogen in connection with a nuclear power plant. We will show the technologies which allow the coupling between a nuclear power plant and hydrogen technologies.
Integrated Drying and Partial Coal Gasification for Low NOX Pulverized Coal Fired Boiler
Authors: Bhattacharya Chittatosh , Banerjee Nilotpal
Published: March 2012

Coal bound moisture is a key issue in pulverized coal fired power generation. Coal being hygroscopic, accumulates considerable surface moisture with seasonal variations. A few varieties of coals are having unusually high inherent as well as surface moisture that affects the pulverizer performance and results lower thermal efficiency of the plant. A proper coal drying is essential for effective pulverization and pneumatic conveyance of coal to furnace. But, the drying capacity is limited by available hot airflow and temperature of hot primary air. Even, use of high-grade coal for blending would not provide the entire useful heat value due to moisture, when used for matching power plant design coal parameters. Besides, the inefficient mining, transportation, stacking and associated coal fleet management deteriorates the “as fired” coal quality affecting cost while purchased on “total moisture and gross heat value” basis. Partial devolatilisation of coal in a controlled heating process, prior combustion in fuel-rich environment ensures better in-furnace flame stability and less residual carbon in product of combustion. It improves the opportunity of a lower flame zone temperature, delivering better control over thermal NOx formation from fuel bound nitrogen. The pulverized coal fired power plants use coal feeders in either gravimetric or volumetric mode of feeding that needs correction for moisture in coal which changes the coal throughput requirement. In this paper an integrated coal drying and partial coal gasification system model is discussed to improve the useful heat value for pulverized coal combustion of high moisture typical power coals so that related improvement in coal throughput can be carried out by application of suitable coal drying mechanism like Partial Flue Gas Recirculation through Pulverizer (PFGR©) for mitigating the coal throughput demand with optimizing available pulverizing capacity along NOx control opportunity without derating steam generation capacity of the boiler.
CFD Simulation of Pollutant Emission in Power Plant Boilers
Authors: Galindo-Garci´a Iva´n F. , Va´zquez-Barraga´n Ana K. , Mani´-Gonza´lez Alejandro G. , Rossano-Roma´n Miguel
Published: March 2012

A computational model is developed in order to investigate pollutant emissions from power plant boilers to the atmosphere. A well-known method of pollutant reduction is the modification of the combustion conditions to prevent their formation, and 3D computational fluid dynamics (CFD) codes provide an effective tool for the analysis of the combustion process. In this paper CFD calculations were performed to analyze the effect of the amount of combustion air on the production and emission of nitrogen oxides, one of the main pollutants produced during the combustion process. For this analysis the appropriate modeling of the chemical and physical phenomena involved is important, because the production and transport of pollutant species strongly depend on the flow and temperature distributions in the furnace. Two case studies are presented: a pulverized coal-firing tangential boiler and a fuel-oil frontal boiler. The CFD calculations adopt a 3D-formulation of the mean flow equations in combination with the standard high-Reynolds-number k-ε turbulence model. The model domain consists of the whole boiler, from the burner nozzles up to the exit of the economizer. Due to their complex geometrical features and computational limitations bank tubes are not modeled individually, but are grouped in a total volume. A porous media region approach is then undertaken to model gas flow and heat transfer in each heat exchanger. Model validation is a difficult task due to the lack of available data from commercial utilities. Validation has been done using routinely measured global parameters. Relatively good agreement is obtained. Results show that increasing the amount of air reduce nitrogen oxides formation for the case of the tangential boiler, however for the frontal boiler case this behavior is not as evident. These results demonstrate that CFD simulations are a viable tool to study the effect some combustion parameters have on the production of pollutants. CFD results may help to establish trends that, in turn, may help to reduce pollutant emissions from power plant boilers.
Influence of Advancements in Gas Turbine Control Systems on Gas Turbine and Combined-Cycle Performance Test Correction Curves
Authors: Schmitt Thomas P. , Banares Christopher R. , Morlang Benjamin D. , Michael Matthew C.
Published: March 2012

Many modern power plants feature gas turbines with advanced control systems that allow a greater level of performance enhancements, over a broader range of the combined-cycle plant’s operating environment, compared to conventional systems. Control system advancements tend to outpace a plant’s construction and commissioning timescale. Often, the control algorithms and settings in place at the final guarantee performance test will differ significantly from those envisioned during the contract agreement phase. As such, the gas turbine’s actual performance response to changes in boundary conditions, such as air temperature and air humidity, will be considerably different than the response illustrated on the initial correction curves. For the sake of technical accuracy, the performance correction curves should be updated to reflect the as-built, as-left behavior of the plant. By providing the most technically accurate curves, the needs of the new plant performance test are satisfied. Also, plant operators receive an accurate means to trend performance over time. The performance correction curves are intended to provide the most technically accurate assurance that the corrected test results are independent of boundary conditions that persist during the performance test. Therefore, after the gas turbine control algorithms and/or settings have been adjusted, the performance correction curves — whether specific to gas turbines or overall combined-cycle plants — should be updated to reflect any change in turbine response. This best practice maintains the highest level of technical accuracy. Failure to employ the available advanced gas turbine control system upgrades can limit the plant performance over the ambient operating regime. Failure to make a corresponding update to the correction curves can cause additional inaccuracy in the performance test’s corrected results. This paper presents a high-level discussion of GE’s recent gas turbine control system advancements, and emphasizes the need to update performance correction curves based on their impact.
Thermal-Structural Analysis of the Super-Heater Tubes of a Unit of 158 MW
Authors: Alfaro-Ayala J. A. , Gallegos-Mun˜oz A. , Olivares-Arriaga A. , Zaleta-Aguilar A. , Vazquez Martinez J. J.
Published: March 2012

The thermal-structural analysis of the super-heater tubes for a 158 MW unit, applying FLUENT® (CFD) and ANSYS® (FEA), is presented. The analysis includes the spacers (union piece between tubes), welding and tubes. The failures of these elements are related with the operation of the unit and the selection of the weld and materials involved in the affected zone. The distribution of temperature in each metal depends of the thermal conductivity and coefficient of thermal expansion, provoking stress concentration in the rigid zones. The CFD study considers a three-dimensional model where the conjugate heat transfer, including internal flow (steam) and external flow (gases), was analyzed to full load of the unit in steady state. In the FEA study, the thermal-structural stresses were analyzed considering the temperature distribution obtained from the CFD study. The results obtained show that the spacer is of greater temperature than the tubes, provoking gradients of temperature through tube walls, spacers and welds. The highest stress located on the interior tube wall (on the direction of plane where the spacer is welded) is attributed to the different thermal dilatation and pressure expansion of the tube, spacer and weld. The study includes the analysis of some geometries of the union piece (spacer) to release the thermal-structural stresses.
SCR Temperature Control With the Integration of the SmartClean Technology in Progress Energy MAYO Station
Authors: Kirkenir Bill , Manay Ati , Matthew Jobi , Tandra Danny , Edenfield John
Published: March 2012

Selective catalytic reduction (SCR) technology is being increasingly applied for controlling emissions of nitrogen oxides (NOx) from coal-fired boilers. For many power plants, temperature control becomes an essential challenge to ensure optimal SCR performance and to keep the material integrity of the SCR structure. Progress Energy MAYO Plant has a tandem boiler design with a Gross Power Generation Capacity of 2 × 400 MW. The plant decided to change their coal source to a lower HHV type PRB coal and integrated Clyde Bergemann’s SmartClean technology to deal with the changes in the coal quality and ensure a stable flue gas temperature going into the SCR. The new SmartClean technology optimized the cleaning to control the Economizer Exit Gas Temperature (EEGT) at a desired set temperature. The results of the performance tests showed that the EEGT control was successful and the temperature profile stabilized after implementing the new SmartClean technology. The new technology derives decisions and changes the cleaning strategy based on the effect of the sootblowers on the heat transfer performance rather than the traditional approach of targeting a static cleanliness level in the boiler. The performance data of the closed loop tests are presented as well as the economical justification of the project.
The Flow Accelerated Corrosion Engineer and the Working Relationship With Disciplines Within the Company’s Organization
Authors: Gusso Donald G.
Published: March 2012

Flow Accelerated Corrosion (FAC) is a fundamental problem for nuclear, fossil, and combined cycle power plants which can result in the loss of power generation, damage to equipment, and personnel injury. These documented events and failures have attracted the attention of utilities, industry groups, and regulatory agencies. The economic impact of FAC in terms of lost power, lost revenue, damaged equipment and components, and personnel injury has gained increased attention. The mechanism of FAC involves the formation and removal of the protective oxide layer from the inside surface of the pipe or equipment. This process occurs in carbon steel piping systems, tanks, and vessels. The FAC process is influenced by flow rate, pH, oxygen content, operating temperature, material of construction, and piping configuration. To oversee and manage Flow Accelerated Corrosion (FAC) in power plants, utilities have assigned personnel the responsibility to manage the FAC program either at the corporate level or a site representative or both. One of the keys in managing FAC is the relationship, interface, and communication with the other disciplines within the organization. Some of these disciplines include Management, Operations, Maintenance, Design Engineering, System Engineering, Water Chemistry, Plant Documentation, and Non-Destructive Examination (NDE). Their responsibilities within the organization and to each other are critical in keeping the plant on-line and minimizing personnel injury. In addition, it is the foundation for maintaining an effective Flow Accelerated Corrosion Program. These relationships and responsibilities within the FAC Program will be discussed in this paper.
The Value of Demand Response (DR) to Mitigate Wind Integration Costs in a Smart Grid
Authors: Kumar Nikhil , Lefton Steven A.
Published: March 2012

In the last five years the electric grid worldwide has seen increasing amounts of installed wind generation capacity. Over the last five years, North America (USA and Canada) has witnessed wind capacity grow at an annual rate of over 30%. At the same time, increasing investments in smart grid technologies have enabled improvements in energy products such as Demand Response (DR). The utility industry, system operators and regulators are investing heavily to understand and determine the impacts of increasing wind penetration on the power system. As explored below, an often neglected, but important point of interest to the authors has been the effect of increased cycling of large fossil, formerly base loaded power plants due to increasing penetration of variable wind or solar power. Various types of DR programs have been implemented by utilities and system operators and these DR programs may be classified based on the time it takes to call upon a DR event or the energy market that the programs are allowed to participate within. Hence, we may have a “slow” DR that participates in a Day-Ahead market and the events are called upon well in advance. On the other hand, “fast” DR programs would participate in Real-Time and Ancillary Services markets. DR from a power dispatch perspective can be considered a “virtual power plant” providing energy, ancillary service and capacity in energy markets. Energy benefits of DR have been explored extensively, especially in terms of reduced fuel costs due to reduction in demand. In this paper we explore the conceptual use and value of DR in providing benefits associated with reduced damage to a fleet of fossil-fueled power plants if it is used to reduce startups and/or load following/cycling.
CFD Analysis of Ventilation Flow for a Scale Model Hydro-Generator
Authors: Toussaint Kristopher , Torriano Federico , Morissette Jean-Franc¸ois , Hudon Claude , Reggio Marcelo
Published: March 2012

In 2006, the first Computational Fluid Dynamics (CFD) simulations of the ventilation of specific hydro-generator components were performed at the Hydro-Que´bec Research Institute (IREQ) and lately the entire ventilation circuit is being investigated. Due to the complexity of flow calculations, a validation process is necessary and for this reason a 1:4 scale model of a hydro-generator has been built at IREQ to get experimental data by means of particle image velocimetry (PIV). This paper presents 2D and 3D simulation results for the scale model obtained with a commercial CFD code and addresses the challenges associated with the application of CFD to hydro-generators. In particular, the effect of rotor-stator interface (RSI) types and configuration is analyzed to determine the approach that best suits this application. Two-dimensional calculations show that the steady state multiple frames of reference (MFR) solution is highly sensitive to the type (frozen rotor (FR) vs. mixing plane (MP)) and location of the RSI. A parametric study is performed where each interface configuration is compared to the transient case results. The MFR-FR interface model produces results that may vary significantly depending on the relative rotor position and the radial location of the RSI in the air gap. The MFR-MP interface model appears to be more coherent with reference values obtained from a transient case, since the radial velocity profiles in the stator are similar. Furthermore with an appropriate radial positioning of the interface, the windage losses are within 20%. Simulations of the complete 3D ventilation circuit revealed a maximum variation of 10% in both total ventilation flow rate and total windage losses, between the RSI configurations studied. However, the relative flow distributions, normalized with respect to the total flow rate, are unaffected by changes in RSI configuration. This paper focuses mainly on sensitivity studies to numerical settings, but this comparison still requires experimental validation before any final conclusions can be made.
Creep Monitoring in High Energy Piping
Authors: Hulshof Harrie , Kraijesteijn Joop
Published: March 2012

High energy piping in power plants and industrial installations have a limited life due to creep and fatigue. Creep in steam pipes and headers are a collection of diffusion processes, driven by temperature and mechanical stress, which cause permanent strain. The surface strain is an objective measure for creep and these can be measured using nondestructive examinations. KEMA developed an inspection technique SPICA (Speckle Pattern Image Correlation Analysis) which makes it possible to measure on stream deformation due to creep in critical areas like the heat-affected zone (HAZ) in welds. This paper discusses the measurement method and results of tests on different scales. Also, a procedure for the application of strain measurements in power plants and creep strain criteria for end of life are discussed.
Flow and Structural Analysis of a Straight and Swept Blade Near Stall Region
Authors: Amano Ryoichi S. , Avdeev Ilya , Das Pradeep Mohan Mohan , Shams Mir Zunaid
Published: March 2012

The aerodynamics of a straight edged and a swept edged blade are investigated using a commercial CFD code. RANS equations with SST k-ω equation were utilized to study the flow separation along the blades span in a stall region. The analysis results will be used to provide inputs to future designs to improve and to enable better prediction of the stall region. The computations were carried out in a narrow wind speed range of 14 m/s to 16 m/s which as per earlier analysis was near the stall point to further understand the locations of flow separations along the blade span. The study provides some insights in to the flow physics in the region around the wind turbine blade. An FE Analysis was also performed to further understand the maximum stress and displacement regions to further provide inputs to future designs. A comparison of maximum stress, deformation and structural vibration modes for the two blades were also done.
Challenges in Designing and Building a 700 MW All-Air-Cooled Steam Electric Power Plant
Authors: Langaker John T. , Hamker Christopher , Wyndrum Ralph
Published: March 2012

Large natural gas fired combined cycle electric power plants, while being an increasingly efficient and cost effective technology, are traditionally large consumers of water resources, while also discharging cooling tower blowdown at a similar rate. Water use is mostly attributed to the heat rejection needs of the gas turbine generator, the steam turbine generator, and the steam cycle condenser. Cooling with air, i.e. dry cooling, instead of water can virtually eliminate the environmental impact associated with water usage. Commissioned in the fall of 2010 with this in mind, the Halton Hills Generating Station located in the Greater Toronto West Area, Ontario, Canada, is a nominally-rated 700 Megawatt combined cycle electric generating station that is 100 percent cooled using various air-cooled heat exchangers. The resulting water consumption and wastewater discharge of this power plant is significantly less than comparably sized electric generating plants that derive cooling from wet methods (i.e, evaporative cooling towers). To incorporate dry cooling into such a power plant, it is necessary to consider several factors that play important roles both during plant design as well as construction and commissioning of the plant equipment, including the dry cooling systems. From the beginning a power plant general arrangement and space must account for dry cooling’s increase plot area requirements; constraints therein may render air cooling an impossible solution. Second, air cooling dictates specific parameters of major and auxiliary equipment operation that must be understood and coordinated upon purchase of such equipment. Until recently traditional wet cooling has driven standard designs, which now, in light of dry cooling’s increase in use, must be re-evaluated in full prior to purchase. Lastly, the construction and commissioning of air-cooling plant equipment is a significant effort which demands good planning and execution.
Practices in Repairing Heat Exchangers
Authors: Al-Khuliawi Fawaz A.
Published: March 2012

The Presentation will introduce Saudi Aramco Heat Exchanger Shop practices in repairing Heat Exchangers that are used in Power and petroleum Industries for mainly two types Shell & Tube and Air Cooled Heat Exchangers. The Presentation will illustrate current challenges in repairing heat exchangers through strategic partnership to maintain reliable service to Saudi Aramco Plants operation. Four success cases will be addressed.
Beyond Smart Grid: Alternatives for Transmission and Low-Cost Firming Storage of Stranded Renewables as Hydrogen and Ammonia Fuels via Underground Pipelines
Authors: Leighty William C. , Holbrook John H.
Published: March 2012

We must soon “run the world on renewables” but cannot, and should not try to, accomplish this entirely with electricity transmission. We need to supply all energy, not just electricity, from diverse renewable energy (RE) resources, both distributed and centralized, where the world’s richest RE resources — of large geographic extent and high intensity — are stranded: far from end-users with inadequate or nonexistent gathering and transmission systems to deliver the energy. Electricity energy storage cannot affordably firm large, intermittent renewables at annual scale, while carbon-free gaseous hydrogen (GH2) and liquid anhydrous ammonia (NH3) fuels can: GH2 in large solution-mined salt caverns, NH3 in surface tanks, both pressurized and refrigerated. “Smart Grid” is emerging as primarily a DSM (demand side management) strategy to encourage energy conservation. Making the electricity grid “smarter” does not: 1. Increase physical transmission capacity; 2. Provide affordable annual-scale firming storage for RE; 3. Solve grid integration problem for large, time-varying RE; 4. Alleviate NIMBY objections to new transmission siting; 5. Reduce the high O&M costs of overhead electric lines. The “smarter” grid may be more vulnerable to cyberattack. Adding storage, control, and quality adjunct devices to the electricity grid, to accommodate very high renewables content, may be technically and economically inferior to GH2 and NH3 RE systems. Thus, we need to look beyond “smart grid”, expanding our concept of “transmission”, to synergistically and simultaneously solve the transmission, firming storage, and RE integration “balancing” problems now severely constraining our progress toward “running the world on renewables”.
Improving the Incremental Regulation of Steam Turbines Equipped With Mechanical Hydraulic Control (MHC) Systems
Authors: Newbury William , DeCrow Steve
Published: March 2012

Prior to 1970, mechanical hydraulic control (MHC) systems were used as the industry standard for operating steam turbine generators in the USA. These systems were primarily designed for safe, reliable, efficient base load operation close to nameplate rating. Today, most steam turbine generators rated at 400 megawatts (MW) or below are required to operate in some form of automatic load following central dispatch control mode. This mode of operation necessitates the need to provide a predictable linear output response to a specific demand input signal within a wide load range. A typical MHC system “Fig.1” performs multiple proportional response functions. The contents of this paper focus on the proportional relationship of the hydraulic operating cylinder stroke relative to the steam flow resulting from control valve lift specific to steam turbines manufactured by the General Electric Co. and Allis Chalmers Co. The purpose of this paper is to raise the level of awareness to: 1. The reasons why most MHC systems have difficulty operating in automatic load following mode. 2. The major factors contributing to this operating problem. 3. A proven methodology to quantify the influence of these major factors. 4. A proven cost effective approach to improving non-linear steam flow without major modifications.
The Effect of Elevated Water Content on Ethanol Combustion: A Feasibility Study
Authors: Breaux Baine B. , Acharya Sumanta
Published: March 2012

In order to make ethanol economically competitive, market forces are demanding that the fuel deliver more energy per dollar invested. The process of distillation accounts for as much as 37% of the energy cost associated with producing bio-ethanol. This paper investigates the possibility of sustaining a combustion reaction with fuel that has a higher water content than is currently accepted as standard. The use of such aqueous fuel in lieu of the more energy expensive alternative could reduce the overhead of producing the fuel and lead to a better financial return. In this study, hydrous ethanol is burned in a continuous flame using a swirl-stabilized combustor with a dump diffuser at the inlet and pressure-orifice atomizing nozzles for fuel injection. The flame is observed as air flow rate is held constant and water content varies from 0% to 40% water. Fundamental relationships between water content and flame temperature, NOx formation, and lean blow out conditions are presented. By characterizing these relationships effectively it may be possible to establish an optimum water content that yields the highest energy delivered per dollar invested.
Formation and Dissociation of Oceanic Methane Hydrate for a Low CO2 Emission Power Generation System
Authors: Maruyama Shigenao , Deguchi Koji , Komiya Atsuki
Published: March 2012

Methane hydrate dissociation is studied using numerical and experimental approaches for a low carbon dioxide (CO2) emission power generation system utilizing methane hydrate. A novel power generation system has been proposed by authors, in which methane gas produced from oceanic methane hydrate reservoir by thermal stimulation method is used as fuels. The performance of the power generation system and the heat loss during the injection of hot seawater to the methane hydrate layer were investigated in previous study. However, the estimation of the methane gas production rate from the methane hydrate reservoir is necessary to evaluate the performance of whole system. In this study, we conducted the numerical simulation of methane hydrate reservoir. In order to evaluate the reaction rate of methane hydrate dissociation, the methane hydrate formation and dissociation experiment was conducted. The result of numerical simulation indicates the necessity of improvement of the production process to supply the heat of hot water effectively. From the experimental result, it comes to see that consideration of the scale effect of the methane hydrate construction is necessary to describe the dissociation rate.
Assessment and Planning of the Electrical Systems in Mexican Refineries by 2014
Authors: Flores Luis Ivan Ruiz , Rodri´guez Marti´nez J. Hugo , Taboada Guillermo D. , Pano Jimenez Javier
Published: March 2012

Nowadays the refining sector in Mexico needs to increase the quantity and quality of produced fuels by installing new process plants for gasoline and ultra low sulphur diesel. These plants require the provision of electricity and steam, among other services to function properly, which can be supplied by the power plants currently installed in each refinery through an expansion of their generation capacity. These power plants need to increase its production of electricity and steam at levels above their installed capacity, which involves the addition of new power generating equipment (gas or steam turbo-generators) as well as the raise of the electrical loads. Currently, the Mexican Petroleum Company (PEMEX) is planning to restructure their electrical and steam systems in order to optimally supply the required services for the production of high quality fuels. In this paper the present status of the original electrical power systems of the refineries is assessed and the electrical integration of new process plants in the typical schemes is analyzed. Also this paper shows the conceptual schemes proposed to restructure the electrical power system for two refineries and the strategic planning focused on implement the modifications required for the integration of new process plants that will demand about 20 MW for each refinery by 2014. The results of the analysis allowed to identify the current conditions of the electrical power systems in the oil refining industry or National Refining Industry (NRI), and thereby to offer technical solutions that could be useful to engineers facing similar projects.